Tanzanian main opposition leader Edward Lowassa was arrested and briefly detained by police on Monday for allegedly holding an illegal meeting in Geita, a gold mining town in the northwest of the country.

Mr Lowassa, a former prime minister and Chadema leader, was in the company of other senior party officials heading to Nkome, an area in Geita, to campaign for their member for a forthcoming civic by-election.

The former premier, together with his five-vehicle entourage, is said to have arrived in Geita at about 3.30pm where he was met by party members and supporters.

Mr Lowassa, who ran against CCM's President John Magufuli in 2015, took sometime to greet residents at a road junction in Geita town when the police arrived and ordered him to remain in his car and head to the local police station.

The residents are reported to have followed him yelling that they were hungry with others chanting “People’s president!".

Tanzania, like other countries in the region, has experienced erratic rainfall leading to crop failures.

At the police station, only one vehicle carrying Mr Lowassa and Prof Mwesiga Baregu, a political scientist, was allowed into the compound.

However, locals are said to have tried to force themselves in against police orders and were met with clubs and belts as officers restrained them.

Police then lobbed tear-gas canisters at the crowd that had swelled after the three-minute chaos.

Mr Lowassa was whisked away through the back door of the station and taken to the office of Geita Regional Police Commander Mponjoli Mwabulambo for questioning.

The road leading to the office of the regional commissioner was manned by Field Force Unit members, who did not allow anyone to enter the compound.

Chadema director of training and organisation Singo Belabenson told The Citizen that Mr Lowassa's entourage had stopped at the marketplace to buy fruits and did not intend to hold a campaign rally there.

The former premier was still at the police commander's station at 11.45pm.

Last year, police banned political meetings saying that rallies called by the opposition are unlawful and likely to breach the peace.

But the president, who said there should be no political activities until the next election in 2020 and people should work, relaxed the ban and allowed only elected officials to conduct meetings within their constituencies.

Government critics however say the ban on political activities is against the Constitution.