Yemeni opposition groups have called on president Saleh to "leave" by the end of 2011 [AFP]

Tens of thousands are continuing with protests in several key cities across Yemen, pressing on with demands that the country's president step down.

The government has suspended classes at the universities in the capital Sanaa and the southern port city of Aden, which have been the focal points for daily demonstrations, the Associated Press reported on Saturday.

The protesters are rallying on the main squares of Sanaa, Aden, and the cities of Taiz and Hadramawt.

They are also demanding an investigation into the killing of four people during protests a day earlier in the northern town of Harf Sofyan.

Yemeni soldiers had opened fire on anti-government protesters on Friday, killing at least four people and wounding around seven others.

Proposal rejected

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Meanwhile, Ali Abudullah Saleh, the country's president, on Friday rejected a proposal by opposition groups that offered him a smooth exit from power by the end of 2011. 

"The president rejected the proposal and is holding on to his previous offer," Yemen's opposition's rotating president Mohammed al-Mutawakil said.

Saleh, who has been in power for 32 years, refuses to step down until his term ends in 2013.

The proposal was made this week by a coalition of opposition groups and religious scholars.

It sought to end the country's political crisis, calling for a "peaceful transition of power" from Saleh by the end of this year. It also called for a probe into the deadly crackdown on the recent anti-government protests.

The proposal also called for steps to change the constitution and rewriting election laws to ensure fair representation in parliament, removing Saleh's relatives from leadership positions in the army and security forces, and a guaranteed right to peaceful protest.

Yemen has been rocked for weeks by daily protests against the government. Shia Houthis, who say they are discriminated against by authorities, announced their support for anti-government protests in early February.

Source: Agencies