Rwanda's senate on Tuesday unanimously approved a draft constitution to allow President Paul Kagame to seek a third term in office, the head of the senate said, clearing the path for a referendum that is not expected to face much opposition.

Kagame, in power since 2000, won widespread praise for his role in ending a genocide in 1994 of some 800,000 people, most of them Tutsis and moderate Hutus, and for his rebuilding efforts after the conflict ceased.

But while praising Rwanda's economic and social development since then, rights groups say the government severely restricts freedom of expression and does not tolerate dissent, charges the government denies.

"The change (of the constitution) was voted for by 26 senators. No one refused it," Bernard Makuza, senate president, said after the vote.

The draft amendments to the constitution have already been approved by the lower house. The amendments could see Kagame, who was first elected president in 2003, staying on until 2034.

READ: Kagame free to rule till 2034

The Democratic Green Party, Rwanda's only one genuine opposition party, which is tiny and has no seats in parliament, has tried to block the amendments through legal action, but the Supreme Court rejected its bid, saying it would depend on the will of the citizens.

READ: Rwanda's main opposition party considers giving up

Critics accuse Kagame, 57, of trampling on media and political freedoms, a charge officials deny. The government says it cannot be blamed if opponents fail to win at the ballot box.

A date for a referendum has yet to be decided.