|Protests against Saleh's rule have slowly spread across Yemen [Reuters]
Yemen's opposition coalition has rejected an offer from the president to form a government of national unity provided that protests against him stop.
Mohammed Saleh al-Qubati, an opposition leader, rejected Ali Abdullah Saleh's offer on Monday, saying that the president should step down instead of offering outdated "tranquilisers".
Thousands more protesters had joined demonstrations against Saleh's 32-year rule earlier on Monday, leading him to offer a government of national unity "within the next 24 hours", government sources have told Al Jazeera.
Hashem Ahelbarra, Al Jazeera's correspondent in Yemen, said that this was a "last ditch effort to try and appease the mounting tension here in the capital and across the country".
"Al Jazeera understands that President Ali Abdullah Saleh has had a crucial meeting with the clerics of Yemen in the presidential palace and he told them that within 24 hours from now he will announce a national unity government," he said.
"He reportedly said that even if the opposition decides not to join him in this government, he will contact independent personalities and invite them to join this national unity government that would lay down the groundwork for dramatic constitutional reforms."
Mohammed al-Sabry, a spokesman for Yemen's umbrella opposition coalition, said that the "opposition decided to stand with the people's demand for the fall of the regime, and there is no going back from that".
Saleh's efforts to stay in power appeared to receive another blow when a senior leader of the Baqil tribe - the second largest in Yemen - called on him to "do what the people want and take important and rapid decisions that meet the demands of the people".
Sheikh Amin al-Okeimy, who is a member of Saleh's ruling Congress Party, said in a statement that the tribe stands by "the people until they achieve ll their goals".
The statement came two days after a pair of powerful chiefs from Saleh's own tribe, Hashid, abandoned him.
Protests against Saleh, a US ally in its fight against al-Qaeda, have spread across the impoverished Arabian Peninsula in the last month.
In the northern cities of Ibb and Hudeida on Monday, thousands of protesters gathered, while at least 10,000 took to the streets in Taiz, 200km south of the capital.
Saleh has promised to step down after national elections in 2013, but that has not stopped the protests.
He told religious leaders on Monday that leaving office cannot be just his decision, but needs also to be that of the people.
"I am ready to form a national unity government" when the opposition names its candidates for government posts, Saleh said, adding that it should happen after protests end.
The president accused his opponents of "planning to reach power through chaos".
He warned that Yemen is going through a difficult period, and if the country collapsed, it "will not split into southern and northern parts, but it will be torn apart to four or five sectors".
The developments in Yemen came as violence against security forces in the south of the country surged.
Local officials said gunmen killed two soldiers in successive attacks, and a prison riot killed one inmate and wounded two guards as four prisoners escaped.