Tanzanian police arrested the leader of the country's main opposition party on Wednesday as he finished addressing a public meeting, his party said.

Rights campaigners have accused the government of President Samia Suluhu Hassan of targeting opponents ahead of a national election late this year. The government denies the accusations.

Tundu Lissu, the chairman of the leading opposition party CHADEMA, has been holding rallies countrywide in recent weeks under the slogan "No Reforms, No Election" to call for reforms in the way the election will be run.

"Tundu Lissu has been arrested by the police in Mbinga district when he had just finished addressing a public meeting. Up to now, it is not known which police station he has been taken to," CHADEMA said on its X account.

"The chairman has been arrested with other party members, and the police officers are dispersing the public using tear gas at the venue."

A regional police commander said he was in a meeting and gave no further comment when contacted by Reuters.

Lissu survived being shot 16 times during an assassination attempt in 2017.