The UN special envoy for Yemen on Saturday urged the country's warring parties to make "decisions that will prove your true intentions", as peace talks resumed in Kuwait City after government delegates abandoned a boycott threat.

Ismail Ould Cheikh Ahmed said the negotiations, back on after a 15-day suspension, would last for two weeks and warned that they may be Yemen's last chance for peace.

"It's time for decisive decisions that will prove your true intentions and national responsibilities to Yemenis," he told a meeting of the two delegations late Saturday.

The envoy said the discussions between Yemen's Huthi rebels and the government of President Abedrabbo Mansour Hadi would focus on strengthening a ceasefire that came into effect on April 11 but has been repeatedly violated.

They would also deal with "forming the military committees that will supervise the withdrawal and handover of weapons... and opening safe passages for humanitarian aid," he said.

Ould Cheikh Ahmed said that over the past two weeks he had held intensive talks in Sanaa, Riyadh and Muscat and met with many dignitaries who declared their support for a final settlement.

"I hope that you will seize this opportunity which could be the last to win the trust of Yemeni people," the UN envoy added.

- Boycott threat -

The talks resumed after Ould Cheikh Ahmed convinced the Yemen government to send its delegation to Kuwait after threatening to pull out of the peace talks which began on April 21.

Earlier in the day, Yemen Foreign Minister Abdulmalek al-Mikhlafi said the government had obtained a "written response to our demands sufficient for the political leadership to decide (on) sending the delegation back to Kuwait".

A well-defined timetable has been agreed that is limited to "withdrawal, handover of arms, return of state institutions, release of prisoners and lifting siege on cities" by the Iran-backed Huthi rebels and their allies, Mikhlafi said.

The deal was struck after two days of talks with Ould Cheikh Ahmed in Riyadh, he said.

It was also agreed that the talks' two-week duration will not be extended and no other issues will be debated, he added.

The rebel delegation of Huthis and representatives of former president Ali Abdullah Saleh's General People's Congress party arrived in Kuwait on Friday.

More than two months of negotiations between President Hadi's Saudi-backed government and the rebels have failed to make any headway.

The government is calling for implementation of UN Security Council Resolution 2216 which requires the rebels and their allies to withdraw from areas they have occupied since 2014, including the capital Sanaa, and hand over heavy weapons.

Hadi had previously warned that his government would boycott the talks if the UN envoy insisted on a roadmap stipulating a unity government that included the insurgents.

His government wants to re-establish its authority across the entire country, much of which is rebel-controlled, and to restart a political transition interrupted when the Huthis seized Sanaa.

More than 6,400 people have been killed in Yemen since a Saudi-led coalition intervened in support of Hadi's government in March last year.

Another 2.8 million people have been displaced and more than 80 percent of the population urgently needs humanitarian aid, according to UN figures.