At least one protester died following overnight clashes with security forces in Yemen [EPA]

Gulf Arab foreign ministers, seeking a resolution to the political crisis in Yemen, have urged Ali Abdullah Saleh, the country's president, to ensure a peaceful transition to his deputy.

Meeting in the Saudi capital Riyadh on Sunday, they also called for the formation of a national unity government - headed by the opposition - to prepare for fresh elections and a new constitution, Al Jazeera's correspondent in Yemen said.

More than 120 people have been killed since protests in Yemen calling for an end to Saleh's rule began on February 11, inspired by popular uprisings in Tunisia and Egypt which toppled long-serving leaders.

The Gulf Co-operation Council (GCC) meeting took place as thousands of protesters continued to demand the resignation of Saleh.

The GCC is made up of Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates.

The Riyadh meeting was called to evaluate the official response of Saleh and Yemen's opposition coalition to the GCC mediation effort.

The developments follow a war of words between Saleh and Qatar, which erupted after the Gulf state's prime minister remarked that mediation would lead to the Yemeni leader standing down.

Saleh had initially accepted an offer by Saudi Arabia and other Gulf states to hold talks with opposition parties in an attempt to resolve the crisis, but the plan stalled when Saleh took exception to Sheikh Hamad bin Jassim bin Jabr Al-Thani's comments and withdrew Yemen's ambassador from Doha.

No dictation

A Gulf diplomat earlier said that Yemen, which is not part of the six-member GCC, now wanted assurances that the group would only mediate and not dictate any outcomes.

"If there is a [mediation] meeting it will be under the auspices of the GCC secretariat under one condition that the GCC will not get involved in the final decision," he said.

"The Yemenis won't agree to the talks in Saudi unless they get a promise from the GCC that they won't get involved."

On the ground, meanwhile, there has been no let-up in the demonstrations against Saleh's 32-year rule.

A mass march to the United Nations building in Sanaa, the capital, was cancelled on Sunday amid fears of reprisals by security forces.

One person was killed and up to 500 people were reportedly injured after security forces using live fire hit dozens of demonstrators in overnight clashes in Sanaa and Taiz, a city in the country's south, medics said.

"One protester died of his wounds late on Saturday," said a medic treating casualties at a makeshift field hospital in Taiz.

In Sanaa, security forces shot and wounded 30 people on Saturday, while 80 others suffered injuries from beatings with batons, medics and demonstrators said.

Another 1,200 people needed treatment for tear-gas inhalation, according to a medical team set up by mostly young protesters who have staged a sit-in at a square near Sanaa University since February.

Source: Al Jazeera and agencies