He said a call by Salah for dialogue fell short of a genuine desire to consider opposing views, pointing to the president's refusal to meet the parliamentarians before they resigned.

"Everyone must be included in a national dialogue, including the Houthis," Jubairi said, referring to insurgents belonging to a sect of Shiite Islam who mounted a violent challenge to the central government last year.

Other parliamentarians who resigned are Ali Abdallah Qadi, an influential relative of the president, tribal leader Abdo Bisher from the Sanaa region and two well-known figures from southern Yemen.

Bisher told Reuters that Saleh "must take quick steps on the ground" to avert more violent challenges to his rule and rising
separatist sentiment in southern Yemen, which was united with the north in the 1990s.

"He has to send a signal. The corrupt must be brought to trial. The authorities cannot keep disregarding human rights," Bisher said. "Otherwise we will not be looking at south Yemen separating, but chaos in the whole country," he added.

Saleh's General Ruling Congress Party still has around 240 members in the 301-strong parliament, which the opposition says is a result of unfair elections and the use of state machinery to elect Saleh's allies.

Saleh said he would not give in to what he described as opponents advocating anarcy.
 

But thousands of Yemeni anti-regime demonstrators defiantly vowed on Wednesday to keep protesting after regime loyalists shot dead two of them.

"Enough! Enough! The criminal attacks during the night!," chanted the mostly young demonstrators encamped at Sanaa University in the capital, after gunmen attacked them during the night, killing two of them and wounding 23, according to witnesses and medics.

Meanwhile, Saleh's General People's Congress, has indefinitely postponed a counter-demonstration which had been announced for Wednesday due to the deaths of protesters in Sanaa, a source close to the party said.

The attack on the rally took place near midnight and followed other clashes Tuesday between the two sides.

Witnesses said government loyalists opened fire on the students, killing two of them and wounding 23 before police arrived and returned fire, sending the attackers fleeing.

Around 1,000 students have been camping since Sunday at a square near Sanaa University, which they have dubbed Al-Huriya (Liberty) Square and where they have erected a huge tent.

The crowd swells during the day as protesters gather to chant slogans demanding Saleh's ouster.

On Tuesday morning the protesters staged a march through the streets and passed near to where Saleh's loyalists are hunkered down, sparking a clash during which the pro-regime group attacked them with daggers and batons.

The students, some of whom were also armed with batons, responded.

Protests demanding the fall of the regime were also staged on Wednesday in Mukallah, in the southern province of Hadramout, witnesses said.

Clashes also broke out on Wednesday between police and separatist demonstrators who had gathered in front of a police station in Aden, Yemen's main southern port city.

Protests have also surfaced in north Yemen this week, where tens of thousands demonstrated in the Houthi stronghold of Saada to demand the president step down.

The Zaidi Shiite rebel movement from 2004 fought six wars with Saleh's government before signing a truce in February 2010.

Saleh, who has been in power for 32 years and is one of the region's great survivors, vowed on Monday not to quit under popular pressure and accused his opponents of fuelling the demonstrations.

"If they want me to quit, I will only leave through the ballot box," he said.