Yemen's former president, Ali Abdullah Saleh, has not left his Sanaa home for nearly a week, fuelling speculation that his rebel allies have effectively placed him under house arrest, officials said Tuesday.

They spoke four days after differences between the two sides boiled over into clashes in the capital, which left a Saleh aide, Col Khaled al-Rodai, and three rebels dead.

The clashes in central Sanaa were followed by the large-scale deployment of forces by the two sides, keeping tensions high.

Three days of talks on defusing the crisis have failed, according to the security and military officials, who are affiliated with both sides of the rebel alliance.

They spoke on condition of anonymity because they were not authorised to brief reporters.

The Houthi rebels are allied with Saleh's forces in a war against Yemen's internationally recognised government and a Saudi-led coalition.

The civil war has killed over 10,000 civilians, displaced 3 million people, and pushed the country to the brink of famine. An outbreak of cholera has killed 2,000 people. The rift within the rebel alliance could further complicate stalled peace efforts.

Gunmen suspected of links to the Houthis on Tuesday beat up Saleh's lawyer and close aide, Mohammed al-Masswary, a vocal critic of the rebels who has frequently accused them of not honouring their part in the alliance.

A statement by Saleh's National Congress party condemned the "criminal" attack.

Saleh and the Houthis have always been unlikely allies.

As president, Saleh had repeatedly gone to war with the Houthis in their northern heartland, but after he stepped down in the wake of Arab Spring protests in 2011 he threw his support behind them.

Security forces loyal to Saleh played a key role in helping the Houthis to sweep down from the north and capture Sanaa in 2014. They later went on to seize much of the country.

The officials said Saleh has not left his home since a tension-fraught celebration by his party in the capital on Thursday.

They said he communicated to the Houthis his intention to attend al-Rodai's funeral on Thursday, but the officials said the Houthis may not allow him to leave.

The officials said differences between the two sides are primarily rooted in the Houthis' belief that Saleh, who ruled Yemen for more than 30 years, was plotting against the rebels with key members of the Saudi-led coalition.

Last week, rebel leader Abdul-Malik al-Houthi made thinly-veiled charges against Saleh and his loyalists, saying his rebels have been "stabbed in the back while fighting the enemy in good faith".

Without mentioning Saleh or forces loyal to him by name, he suggested that they were not fighting pro-government forces in earnest.

Saleh dismissed the charges and complained of what he called the domination of decision-making by the Houthis' Revolutionary Committees instead of the National Salvation government the two sides have jointly set up.