US Defense Secretary Mark Esper signed a 10-year military cooperation deal with Tunis Wednesday during his first stop on a regional tour, hailing US-Tunisia collaboration over the conflict in neighbouring Libya.

The past decade has seen growing cooperation between the Pentagon and Tunisia, particularly on counter-terror training and securing the North African country's long border with Libya, where jihadist groups operate and world powers back rival sides in a complex war.

"We look forward to expanding this relationship to help Tunisia protect its maritime ports and land borders, deter terrorism and keep the corrosive efforts of autocratic regimes out of your country," Esper said in a speech after meeting President Kais Saied.

Speaking at a cemetery in Carthage housing the remains of over 2,800 American soldiers, mostly killed in World War II, he warned of the worldwide threat posed by "violent extremists".

Esper also accused US rivals China and Russia of continuing "to intimidate and coerce their neighbours while expanding their authoritarian influence worldwide, including on this continent."

He said Moscow and Beijing's "malign, coercive, and predatory behaviour" aimed to "undermine African institutions".

Washington in 2015 classified Tunisia as a Major Non-NATO Ally, allowing for reinforced military cooperation.

The two sides regularly hold joint exercises, and since 2011 Washington has invested more than $1 billion in the Tunisian military, according to the US Africa Command, Africom.

The deal signed Wednesday, full details of which have not been disclosed, lasts a decade and covers training and after-sales service of sophisticated American weapons, said officials in Esper's entourage.

Tunisia in 2016 denied a Washington Post report that it had allowed the US to operate drones from its territory for missions in Libya against the Islamic State jihadist group.

But a court martial in 2017 in a case of sexual harassment by an American officer, reported in the US defence press, publicly confirmed the presence of an American squadron operating drones from within a Tunisian base in the northern region of Bizerte.

New US interest

The US has "regained interest" in longtime allies Tunisia and Morocco, Tunisian analyst Youssef Cherif said, citing the growing clout of jihadist groups in Libya and the Sahel region since the fall of former Libyan dictator Moamer Kadhafi.

"But Tunisia does not seem to have given its approval to use its airspace and its territory to conduct attacks," he told AFP.

In May, the head of Africom said the US would send more troops to the country in light of the deteriorating situation in Libya, triggering an outcry in Tunisia.

Africom later clarified that it was only deploying "a small training unit" that would not engage in combat missions, and the Tunisian government said there were no plans for an American base in the country.

Esper also met his Tunisian counterpart Ibrahim Bartagi and gave him a replica of a pistol belonging to George Washington, a military leader who became the first president of the United States.

Presenting the gift, Esper said it was to remind Bartagi of the "importance of the civilian control of the military, the importance of an apolitical military."

Esper was set to visit neighbouring Algeria on Thursday, becoming the first US defense secretary to do so since Donald Rumsfeld in 2006.

Esper will then head to Morocco, the other US Major Non-NATO Ally in the Maghreb region.