A protester displays the message 'Irhal' (leave) written on his arm, meant for President Saleh [Reuters]

Two students have been killed in Yemen after more than 1,000 anti-government protesters rallied near Sanaa University.

Witnesses said supporters of Ali Abdullah Saleh, the Yemeni president, opened fire at the protesters late on Tuesday night.

Tom Finn, the editor of Yemen Times, quoted a doctor as saying the two students died from bullet wounds and that 20 others were injured, some by bullets and some by rocks being thrown.

Finn told Al Jazeera that police had surrounded the scene and at least five ambulances had left carrying the injured. 

Earlier in the day, clashes broke out as a crowd of about 4,000 anti-government protesters moved close to where Saleh's loyalists were bunkered down.

About 1,000 students had spent a second night camped at a square near Sanaa University, dubbed Al-Huriya (Liberty) Square, where they have erected a huge tent.

Across the country, tens of thousands rallied on Tuesday calling for Saleh's resignation.

Continued violence

Demonstrators, inspired by revolts in Tunisia and Egypt, have been protesting for almost two weeks against the rule of Saleh, in power since 1978.

On Monday, witnesses said a teenager was killed and four people wounded in a clash with soldiers in the country's southern city of Aden.

Officers stood by as demonstrators marched in the eastern town of al-Shiher, chanting "Down, down with Saleh".

In Taiz, Yemen's second-largest city, thousands of protesters marched in the Safir Square. An activist, Ahmed Ghilan, said hundreds have been camping in the square for more than a week, renaming it "Freedom Square".

In Aden, schools closed, most government employees were not working and many shops were closed as hundreds gathered for another round of protests.

But mounting pressure has so far yielded little result as Saleh insists he will only step down after national elections are held in 2013.

He has said protesters demanding an end to his rule could not achieve their goal through "anarchy and killing".

He said on Monday that he had ordered troops not to fire at anti-government protesters, except in self-defence, but medical officials say at least 12 people had been killed in demonstrations before the latest deaths were reported on Tuesday.

A spokesman for the opposition rebuffed Saleh's offer of dialogue, while an influential group of Muslim religious leaders called for a national unity government that would lead the country to elections.

Source: Agencies