Yemen's ex-president Ali Abdullah Saleh dismissed UN sanctions against him and senior Huthi rebel chiefs, pulling his party Saturday from a new cabinet and plunging the country into deeper chaos.

Saleh's move came as Al-Qaeda claimed it had killed dozens of Shiite rebels and tried to assassinate the US ambassador, and the rebels also rejected a new government announced on Friday.

Yemen has been dogged by instability since an Arab Spring-inspired uprising forced Saleh from power in 2012, with the Huthi rebels and Al-Qaeda seeking to fill the power vacuum.

The turmoil has raised fears that the Arabian Peninsula nation, which neighbours oil-flush Saudi Arabia and lies on the key shipping route from the Suez Canal to the Gulf, may become a failed state.

The new cabinet was formed shortly before the UN Security Council Friday slapped sanctions against the influential former president Saleh and two rebel commanders for threatening peace.

The US-proposed UN measures included a visa ban and asset freeze.

The Huthis are widely thought to be backed by Saleh, with Washington accusing him of being "behind the attempts to cause chaos throughout Yemen" by using them to weaken the government and "create enough instability to stage a coup".

A day after the UN measures were adopted, Saleh told members of his General People's Congress (GPC) they were "rejected".

The GPC said the UN decision to penalise Saleh for allegedly obstructing the political process is "strange", insisting that the former strongman "stepped down peacefully" for the sake of a political compromise.

Saleh said he was willing to give up the immunity he was granted after stepping down in February 2012 following nationwide protests, and to face Yemeni justice.

"Find any (corruption) files, refer them to justice and lift the immunity. I will be there to appear in court," he told the GPC.

The GPC also said it had not been consulted about the long-awaited cabinet, and urged party nominees to turn down their assigned ministries.

The Huthi rebels similarly rejected the new government, instead demanding a reshuffle to dismiss ministers they consider unqualified or corrupt.

Though the rebels, also known as Ansarullah, are not directly represented, six of the new ministers are considered close to the insurgents.

Despite this, the rebels said Saturday the new government "is in violation of the peace agreement... and a clear obstruction to the political process in favour of private and narrow interests".

The Security Council, in a statement, urged political forces in Yemen to unite, encouraging "all parties to participate peacefully and constructively in taking forward this transition".

"The members of the Security Council underscored the importance of moving forward with an inclusive transition process that represents all of Yemen's diverse communities."

Al-Qaeda claimed twin attacks early Saturday that it said killed "dozens" of Huthis in the central region of Rada, where the Sunni Muslim jihadists have halted a rapid territorial advance by their Shiite rivals.

Al-Qaeda also said it had tried to kill US ambassador Matthew Tueller, but the two bombs were detected "minutes before their detonation".

The devices were planted Thursday outside President Abdrabuh Mansur Hadi's residence, the media arm of Al-Qaeda's Yemen branch said in a statement on Twitter.

There was no official confirmation of the failed plot.

Earlier, Saleh's GPC also sacked Hadi from its leadership, apparently in retaliation after accusations he had solicited the sanctions.

The UN Security Council in its statement expressed support for Hadi, seen by Washington as a key ally in the fight against Al-Qaeda, and Prime Minister Khaled Bahah.

The new 36-member cabinet was formed as part of a UN-brokered peace deal under which the Huthis are supposed to withdraw from Sanaa, which they seized on September 21.

On November 1, the main parties signed an agreement brokered by UN envoy to Yemen Jamal Benomar for the formation of a government of technocrats.

Rebel representatives and their rivals, the Sunni Al-Islah (Reform) Islamic party, mandated Hadi to form a government and committed to support it.

Washington had welcomed the new cabinet.

"This multi-party cabinet must represent the strength of Yemeni unity over individual and partisan interests that may seek to derail the goals of a nation," US National Security Council spokeswoman Bernadette Meehan said.

Benomar has warned in an interview with AFP that without the rapid formation of a government, tensions between Shiites and Sunnis were likely to increase, sinking the country deeper into crisis.