Opposition leader who survived an attack in 2017 returns home three months before the country heads to the polls.

Prominent opposition leader and presidential hopeful Tundu Lissu has returned to Tanzania to a rousing welcome, three years after narrowly surviving an assassination attempt.

Chanting "president, president", hundreds of cheering supporters gathered on Monday at an airport in Dar-es-Salaam to greet the 52-year-old, who had been living in self-imposed exile in Belgium.

Lissu fled the country after being shot 16 times by unknown gunmen outside his home in the administrative capital, Dodoma, in September 2017.

A fiery critic of Tanzanian President John Magufuli, Lissu had had a series of run-ins with the police in the months before the gun attack. He was arrested several times, accused of insulting the president - whom he had called a "dictator" over alleged assaults on the opposition and the media and disturbing public order.

Following the assassination attempt, Magufuli expressed shock at the news and ordered an investigation. Three years on, the gunmen remain at large.

"The government should ensure his safety given his shooting in 2017," Oryem Nyeko, a researcher with Human Rights Watch, told Al Jazeera following Lissu's return to Tanzania.

Lissu, a member of the main opposition Chadema party, has declared his interest in running for president in Tanzania's highly anticipated election in October.

If picked by Chadema, he will run against Magufuli, of the Chama Cha Mapinduzi (CCM) party.

The president was plucked from the relative obscurity of the Ministry of Works to lead the CCM ticket in the last election thanks to his scrupulous reputation and a work ethic that earned him the nickname "The Bulldozer". He won the hotly contested vote in 2015 on promises to root out corruption and improve infrastructure.

His time in office, however, has drawn criticism from the opposition and rights groups who accuse him of narrowing freedoms and repressing political dissent, including by stifling independent journalism and severely restricting the activities of NGOs. The government denies the allegations.

"The space for government critics and political opposition in Tanzania has been shrinking dramatically since 2015, and we seem to be seeing a continuation of that as we get closer to the elections," Nyeko said, noting "an increase in restrictions towards the opposition".

Last month, opposition leader Zitto Kabwe was freed on bail after he and several members of his Wazalendo Alliance for Transparency and Change (ACT Wazalendo) were arrested for holding an illegal assembly.

Earlier in June, Chadema leader Freeman Mbowe was allegedly beaten and hospitalised in what his party said was a "politically motivated" attack. Tanzanian police cast doubt on the allegations.

Meanwhile, authorities on June 23 revoked the licence of Tanzania Daima, an opposition-leaning daily, accusing it of spreading false information among others.

Three months before the vote, Nyeko called on the government to "make sure that the environment for critics, the media, the opposition and NGOs is open".

He said: "That means the government should refrain from arresting critics, suspending or closing media houses, or implanting the myriad of restrictive laws that it has in the past used to clamp down on people that have differing opinions."

For his part, Magufuli has promised a transparent vote.

"I want to assure everyone that the elections will be free and fair, for all political parties," Magufuli told legislators as he dissolved Parliament in June.

But Kabwe criticised what he said was a lack of a level playing field and repeated calls for the formation of an independent electoral commission.

"[The] CCM government under President Magufuli has narrowed the civic space for the last five years," he told Al Jazeera.

"It is sad that Tanzanians are not free to air their views. Freedom of association and other fundamental freedoms are curtailed, and people are very angry."

The opposition has repeatedly questioned the government's handling of the pandemic, accusing it of failing to inform the public on its true extent. Authorities have not updated the country's official number of COVID-19 infections in three months, while Magufuli has declared the disease defeated.

Besides voting for president, Tanzanians on October 28 will also head to the polls to elect members of parliament and local Councillors. The election commission has said campaigning will run from August 26 to October 27.

"I believe that if the opposition work together and form a strong coalition, CCM can be defeated," Kabwe said.

"I hope we will be able to have a single presidential candidate and divide constituencies in a manner that the opposition will not divide their votes. The election is winnable," he added.