Tanzania's six main political parties have agreed to work together to fight rising "authoritarianism" in the country.

After a two-day meeting on the island of Zanzibar, leaders and top officials of the parties issued a joint statement criticising President John Magufuli for overseeing what they said was a repressive government that branded critics as "unpatriotic traitors".

Mr Magufuli, nicknamed "The Bulldozer", came to power in 2015 and was initially praised for his anti-corruption stance, but critics have since accused him of growing intolerance.

His government has banned some media organisations for what it deems as their anti-government coverage and harassed opposition leaders and activists.

The opposition statement, issued on Tuesday, said:

The historic meeting here in Zanzibar is a reflection of the extent to which the democratic and human rights situation in our country has changed, thereby leading to unprecedented actions on our side in response."

It also highlighted the banning of parliament proceedings coverage and the curbing of opposition activities:

"The situation is no longer tolerable. Enough is enough!"

The opposition leaders said two of their colleagues, one in jail and another in hospital after an assassination attempt, supported their statement.

Next year would be a time to reclaim "our democracy and taking back our powers and rights as enshrined in the constitution", the statement added.

To do this the leaders said they planned to hold public rallies across Tanzania and said the government should take them to court if it thought their activities were unlawful.