|The protesters, most of them based in the capital Sanaa, are demanding the ouster of president Saleh [AFP]
Yemen's opposition has proposed a transition plan which would see the country's longtime president hand power to a vice-president while steps are taken towards a national unity government and new elections.
As protests continued across the country calling for Abdullah Ali Saleh to step down, opposition officials said on Saturday that he had yet to respond to the five-point plan.
The president, in power for 32 years, has said he is prepared to leave eventually but an abrupt exit would cause chaos.
On Saturday, he thanked thousands of supporters gathered near the presidential palace for backing the constitution.
"I salute you for your heroic stand and thank you for supporting constitutional legitimacy," he told the crowd amid a sea of his portraits and banners supporting his continued rule.
Yet in the southern province of Aden, thousands of anti-government protesters clashed with anti-riot police backed by tanks.
Protesters demanding the ouster of the president called for a general strike on Saturday and witnesses said many of residents responded by not going to work. Public transport shut down and many shops were closed.
Demonstrators set tyres on fire, sending black smoke in the sky. Troops fired in the air to disperse young people who had erected barricades with large rocks at the entrance of main roads to prevent tanks from moving, witnesses said.
And in the western port of Hudaida, seven protesters were wounded when riot police used batons and teargas to disperse demonstrators calling for Saleh's resignation, residents said.
Saleh has warned that if he is ousted, Yemen will descend into chaos and boost the al-Qaeda presence already in the country.
The opposition plan would see the army and security forces restructured by a vice-president acting as temporary president.
Wide discussions could then be held on constitutional changes, a unity government and new elections, Yemen's opposition coalition said in a statement.
"President Saleh and his entourage are still involved in their crimes and continue to refuse to understand the demands of the people," the opposition said.
Days earlier, Saleh made a fresh offer to demonstrators, proposing he stays in office until elections are held and that he will transfer his powers to a caretaker government.
The offer was made on Tuesday at a meeting with Mohammed al-Yadoumi, head of the Islah party. It was the first time the president had dealt with Islah, once a partner in his government, an opposition spokesmen said.
"The opposition could pick a head of government of its own choosing and there would be parliamentary elections by the end of the year," an opposition source said of Saleh's offer.
The opposition promptly rejected the offer, with a spokesman calling it "an attempt to prolong the survival of regime".
Weeks of protests by many thousands in Sanaa, the capital, and other cities have sent Saleh's rule to the brink of collapse.
However, the United States and top oil producer Saudi Arabia, a key Yemen supporter, are worried over who could succeed their ally. They have long regarded Saleh as a bulwark of stability who can keep al-Qaeda from extending its foothold in an Arabian Peninsula country.
Yemen's al-Qaeda wing claimed responsibility for a foiled attempt in late 2009 to blow up an airliner bound for Detroit, and for US-bound cargo bombs sent in October 2010.
Some 82 people have been killed during the protests so far, including 52 people shot by government snipers on March 18.