Ugandan lawmakers have postponed a bill to extend President Yoweri Museveni's rule after protesters clashed with police in Kampala.

Addressing a raucous session in parliament on Thursday, Speaker Jacob Oulanyah said the legislation was "bringing tension" and would come back on another, unspecified date.

Police on Thursday used tear gas and arrested dozens of people who had gathered at Makerere University in the capital Kampala to stage a protest march against the controversial bill.

Ugandan police had warned on Wednesday that no protests would be allowed, either for or against the bill.

On Thursday, they besieged the offices of two organizations which are allegedly orchestrating anti-government protests, searching the offices for incriminating evidence, police spokesman Asan Kasingye said.

Presidency age bill

Uganda's constitution bars anyone over the age of 75 from seeking the presidency.

The draft bill aiming to remove the age limit was scheduled to go before parliament on Thursday, but was postponed due to chaos in the chamber.

The 73-year-old President Museveni is now ineligible to run for president again in 2021 if the age restriction remains.

In parliament, lawmakers on Thursday heckled and threatened each other as the bill was being introduced.

The parliamentary spokesperson postponed the introduction of the bill and said it will likely be reviewed next week.

Museveni's party holds the majority of parliamentary seats and the bill is expected to pass.

Museveni, who has been at the helm of the country since 1986 and is credited with restoring peace and stability to the African nation, won re-election last year in a poll marred by allegations of vote fraud and intimidation by the security forces.

Although he has warned in the past that Africa's problem was the leaders "who want to overstay in power," he has lately said he was speaking about leaders who were not elected.