Yemen's Huthi rebels mounted a show of strength in Sanaa on Thursday, holding a mass memorial ceremony for comrades killed in this month's battle for control of the capital.

Witnesses said clashes erupted again Thursday around the Sanaa residence of Tarek Saleh, a nephew of slain ex-president Ali Abdullah Saleh.

The Huthis ousted forces loyal to Saleh in ferocious fighting after the collapse of their uneasy three-year alliance -- and then killed him as he fled.

Hundreds of rebel supporters thronged Sabaeen Square in the city centre as fighters in fatigues stood guard over rows of coffins wrapped in the national flag.

More than 230 people, including civilians, were killed in the fighting between the Huthis and Saleh's loyalists, according to the International Committee of the Red Cross.

Rebel commander Yahya Mahdi told AFP the Huthis were still holding Saleh's body.

The rebel-controlled interior ministry has launched a campaign to seize the assets of leading figures in Saleh's General People's Congress, the Huthis' Almasirah television said.

Saleh's party said many of its members had been detained and some executed by the rebels, but there was no immediate independent confirmation.

Sanaa residents have been stocking up on basic goods for fear of further violence. The United Nations has appealed for calm.

A Saudi-led coalition, which has been battling the rebels since March 2015, imposed a blockade on rebel-held ports early last month after a missile was fired at Riyadh airport.

US President Donald Trump took the rare step on Wednesday of publicly demanding that ally Saudi Arabia immediately allow aid into rebel-held areas.