New details emerged on Friday about an American plane, owned by a small community bank in Utah and mysteriously parked this week at Tehran’s airport, showing that it had been leased by a Ghanaian mining company owned by a brother of Ghana’s president.

Buffeted by questions about why an American plane was in Tehran, Iran’s Foreign Ministry said on Friday that the plane had been used to transport top Ghanaian officials as part of a broader push to expand cooperation between the two countries.

The visit comes as Iran seeks to cultivate close relations with West African countries including Ghana, which also enjoys warm relations with the United States. In what seemed like an indirect reference to the chilly relationship between the United States and Iran, Marziyeh Afkham, the Foreign Ministry spokeswoman who announced the purpose of the visit in a statement, emphasized that the passengers and crew “were all non-American.”

Still, the American-flagged plane, a Bombardier jetliner powered by two General Electric engines, was an extraordinary sight in Iran and illustrated how aircraft operators can obscure themselves under United States rules that some American law enforcement officials find troubling. Iran has been so ostracized by the West over the years, particularly by the United States, that typically permission is required from officials in Washington for such a plane to fly there.

A confidential document reviewed by The New York Times showed that the plane is held in a trust by the Bank of Utah on behalf of the mining company, Engineers and Planners, which is based in Accra, the Ghanaian capital. As the beneficiary of the trust, the company operates the plane. The company’s chief executive is Ibrahim Mahama, a brother of President John Dramani Mahama.

The plane departed Iran on Thursday, Ms. Afkham said, after a series of meetings between the Ghanaian delegation and top Iranian officials.

Reached by telephone Friday night, Ibrahim Mahama said, “Let me get some details and I will call you back.”

The plane has a history of intercontinental travel, according to images posted on the Internet by amateur photographers who make a sport of snapping airport takeoffs and landings to chronicle flight itineraries. Six months before the plane was spotted on Tuesday parked at the V.I.P. section of Mehrabad Airport in Tehran, it was seen leaving a London-area airport bound for Accra. The plane can be easily identified by the call letters on its tail engines, N604EP.

While the Ghanaian company is not subject to the patchwork of sanction rules constricting trade between Iran and the United States, the Utah bank, based in Ogden, is bound by sanctions.

To travel to Iran, the aircraft would typically need a license from the Treasury Department’s Office of Foreign Assets Control, the primary enforcer of American sanctions against Iran. With its American engines, the plane would also typically have to obtain a separate license from the Commerce Department.

The Office of Foreign Assets Control did not issue a license for the plane’s flight to Iran, according to two people briefed on the matter, raising questions about whether its flight had flouted American law. Treasury officials declined to comment.

Questions about whether a license was even required are compounded by federal aviation regulations that can shroud the identity of a plane’s operators. In the case of this plane, the information held in a vast database maintained by the Federal Aviation Administration was limited. The trustee — in this instance, the Bank of Utah — was the sole entity recorded as owner.

The bank, though, was acting as a trustee on behalf of the Ghanaian company, according to a copy of the trust agreement, signed on Sept. 11, 2013. Through the complicated legal pact, the title to the aircraft is held by the Bank of Utah, an arrangement that enables foreign corporations, dignitaries and others to invest in and lease planes that fly freely within the United States, and throughout the world. To operate the plane, the Ghanaian company leases it.

Iran has made no secret of its desire to strengthen relations in Africa. Last April, President Mahmoud Ahmadinejad visited three West African countries — Niger, a leading producer of uranium, Benin and Ghana. The trip to Niger in particular raised speculation that Mr. Ahmadinejad was looking for sources of uranium for Iran’s disputed nuclear program, a major reason for the regimen of Western sanctions imposed on the country.

In February, Iran invited Ghana’s president to visit Tehran for what local news reports called discussions of “issues of mutual interests.”

In Ghana, the aircraft spotted in Tehran this week became the object of wide speculation after local media reports tying the plane to President Mahama. In June 2012, the mining company, which contracts with mines in northern Liberia and Congo, issued a news release denying reports that the president, who was technically still vice president at the time, had acquired the plane.

But in the denial, the company provided a window into how the plane is used, “The company has entered into an agreement with an American company to provide it with air services using a Challenger 600 aircraft.” The pact, the company said, enables “mining companies, oil service companies and other corporate institutions” to rent the plane.

None of these other companies, the actual entities flying the plane, appear on the trust document.

Such opacity troubles some American law enforcement officials, according to several people with direct knowledge of the matter. The fear, these people say, is that the trust arrangements could enable questionable actors to quietly lease private planes. While the F.A.A. says it knows the actual owners of every aircraft, the trust structure can enable a tenuous chain, with one operator leasing the plane to another company, and another, with the details far from public view.

Former federal officials, who spoke on the condition of anonymity, said they believed that the plane has been used to transport President Mahama before. They based that conjecture partly on the plane’s known itineraries from photos posted online.

One image captured the plane flying to the World Economic Forum in Davos, Switzerland, where President Mahama spoke in September. The Ghanaian president was also in London last October when the aircraft was spotted leaving there for Accra.

The aircraft has changed hands several times, according to contracts reviewed by The Times. They provide a family tree of sorts, showing the plane was made by the Canadian company, Bombardier, in 2000. From there, it was leased to a German travel company, and later by a shipping company executive.