Yemen's Shia Houthi rebels and their allies have agreed to join delayed UN-brokered peace talks in Kuwait, their representatives said on Wednesday.

The rebels agreed to join the talks after receiving assurances from the UN envoy and ambassadors that a ceasefire in effect since April 11 would be respected by loyalist forces, the rebels' Al-Masirah television quoted Houthi representative Saleh al-Sammad as saying. 

Mahdi al-Mashat, a representative of rebel leader Abdulmalik al-Houthi, said the rebels had been assured that the agenda for the talks would be "clear and tackle issues that could help achieve peaceful solutions".

Writing on Facebook, Mashat warned however that "we will have the right to suspend our participation" if the assurances are not met.

He said Houthi representatives would leave at "noon tomorrow" but it was unclear whether he was referring to Wednesday or Thursday.

A representative of the rebel-allied General People's Congress party, Yasser Alawadi, said on Twitter that his delegation would travel to Kuwait on Thursday.

The talks, which were set to open in Kuwait on Monday, were delayed after the insurgents failed to show up over alleged Saudi violations of the ceasefire.

UN Secretary General Ban Ki-moon on Tuesday urged the government and the rebels to engage with his envoy "so that talks can start without further delay".

A Western diplomat in Kuwait has said that representatives of the five permanent members of the UN Security Council sent a message to the rebels saying they "understand their fears" and urging them to "quickly join" the talks.

Previous attempts at peace talks -- including a failed round in January -- have been unable to stop Yemen's conflict, which the United Nations says has killed more than 6,400 people and forced almost 2.8 million from their homes.