Kenyan police on Tuesday fired teargas at hundreds of demonstrators protesting against the proposed size of a coalition government, as pressure mounted on the president and prime minister-designate to name a cabinet.

President Mwai Kibaki and future prime minister Raila Odinga signed a power-sharing deal last month but have been wrangling over who will get key ministries and the size of the cabinet.

The president has suggested a 44-member cabinet while Odinga says it should consist of no more than 34 members.

Chanting "No more than 24", protesters planted a tree at the capital's Uhuru park but were stopped by riot police from delivering a letter to the office of the president.

The march was organised by a consortium of human rights groups who are campaigning for a cabinet of 24 ministers.

"As the march started, the police fired teargas at us. It was not provoked. We just saw the gas canisters flying everywhere," said a protester who asked not to be named.

Each side has blamed the other for blocking the implementation of the agreement to end a crisis that killed at least 1,200 people in ethnic violence after Kibaki's disputed December 27 election win.

"Militia groups in the country are re-organising themselves in readiness for war because they don't know if the impasse is going to be resolved any time soon," said Violet Barassa, a human rights activist.

The post-election fighting also damaged east Africa's largest economy, leading the government to drop its growth forecast to 6 percent from 6.9 percent.

Anti-corruption body Transparency International (TI) said a bloated cabinet would punish Kenyan taxpayers.

"It is of grave concern for a country that sustained extensive economic losses ... to consider a bloated cabinet that would cost Kenyans an estimated 4 billion shillings annually," Richard Leakey, the TI-Kenya chair and famed palaeontologist said.

Leakey, the head of the civil service under former President Daniel arap Moi, said his experience showed that the country required 15 to 20 ministries to function efficiently.