Yemen's opposition has rejected a Gulf Arab initiative for Ali Abdullah Saleh to step down as president, because it appears to offer him immunity from prosecution, while Saleh himself has welcomed the plan.
A GCC statement on Sunday talked of "the formation of a national unity government under the leadership of the opposition which has the right to form committees ... to draw up a constitution and hold elections".
Speaking on Monday, Mohammed al-Sabry, an opposition spokesman, said: "Who would be a fool to offer guarantees to a regime that kills peaceful protesters? Our principal demand is that Saleh leaves first."
Saleh has welcomed "efforts" by members of the Gulf Co-operation Council (GCC) to end his country's political crisis, according to a statement from his office earlier in the day.
"In compliance with statements made several times ... the president has no reservation against transferring power peacefully and smoothly within the framework of the constitution," the statement said.
The response did not make clear whether Saleh accepted the GCC proposal for him to step down and ensure a peaceful transition of power to his deputy, Abdrabuh Mansur Hadi.
The proposal said all parties should "stop all forms of revenge .. and [legal] pursuance, through guarantees offered" - wording that appeared to offer Saleh assurances of no prosecution for him or his family once he leaves office.
Diplomatic sources said Saleh has dragged his heels for weeks over US attempts to get him to agree to step down and end protests crippling the country.
'Within the constitution'
Saleh has warned of civil war and the break-up of Yemen if he is forced to leave power before organising parliamentary and presidential polls over the next year.
Al Jazeera's correspondent in Sanaa said: "This has always been his position - the key words are 'within the constitution' which could either mean through elections at the end of the year, or if he chooses to resign it must be accepted by parliament.
"In which case, as we saw with the emergency law a few weeks ago, he can easily swing to make sure they don't accept his resignation."
Speaking to Al Jazeera, Najib Ghaniem, a senior member of the opposition Islah party, said: "We are only interested in the end to the agony of our people.
"If this initiative means that Saleh steps down, then all issues can be put on the table to discuss later on."
Saleh has been in power since 1978 and has faced fierce protests demanding his departure since late January.
On Friday, he rejected a proposal for his exit, made by Sheikh Hamad bin Jassim bin Jabr Al-Thani, Qatar's prime minister, as a "blatant interference in Yemeni affairs".
His statement came after Sheikh Hamad bin Jassim said that the GCC member countries "hope to reach a deal with the Yemeni president to step down".
Against this backdrop of diplomatic developments, tens of thousands of people filled the streets of Sanaa, Taiz, Hudaida, Ibb and the southeastern province of Hadramut to protest against the GCC plan on Monday, witnesses said.
With more than 100 protesters killed as security forces tried to break up the demonstrations with tear gas and live fire, activists say they want to see legal action against Saleh and his sons, who occupy key security and political posts.
Saleh has been manoeuvring to win guarantees that he and his sons do not face prosecution.
Speaking to Al Jazeera, Mahjoob Zweiri, a professor of Middle Eastern history at Qatar University, said: "It is very difficult to say that what he [Saleh] is saying now is a positive response to the [GCC] initiative.
"I see that now Ali Abdullah Saleh is worried, he is under increased pressure from Washington, from EU, from GCC.
"There has been a decision made by Washington that he should go, and he was relying on getting support from Washington."
Saleh had sought Saudi mediation for some weeks, but Gulf diplomatic sources have said the kingdom was finally prompted by concern over the deteriorating security situation in its southern neighbour.
Saudi Arabia, the world's biggest oil exporter, is the main financier of the Yemeni government as well as many Yemeni tribes on its border.
Many leaders in the region became convinced that Saleh is an obstacle to stability in a country that overlooks a shipping lane where over three million barrels of oil pass daily.