By Mohamed Sudam
SANAA (Reuters) - The United States warned citizens in Yemen on Sunday to consider departing as protests seeking the ouster of President Ali Abdullah Saleh gather momentum, saying the security risk in the impoverished state was extremely high.
Tens of thousands of protesters have camped out in many major Yemeni cities, their tone hardening daily, and protests turned to clashes in the town of Ibb on Sunday when government loyalists attacked protesters with sticks and stones.
"The Department (of State) urges U.S. citizens not to travel to Yemen. U.S. citizens currently in Yemen should consider departing," the U.S. State Department said in a travel warning.
"The security threat level in Yemen is extremely high due to terrorist activities and civil unrest."
The growing Yemeni protests, and a series of defections from Saleh's allies, have added pressure on Saleh to end his three-decade rule. Neither side appears willing to compromise.
Protesters want Saleh to step down by the end of this year, if not sooner, while the president is sticking to an earlier pledge to leave office only when his current term ends in 2013.
Yemen, a neighbor of Saudi Arabia, was teetering on the brink of failed statehood even before recent protests, with Saleh struggling to cement a truce with Shi'ite rebels in the north and quell a secessionist rebellion in the south.
Analysts say the recent protests, inspired by unrest that has toppled the leaders of Egypt and Tunisia and sparked an insurrection in Libya, may be reaching a point where it will be difficult for Saleh, an astute politician, to cling to power.
"The country is on the brink of imploding," said Dubai-based security analyst Theodore Karasik. "This popular uprising is going to hit some kind of crescendo and you might have an outbreak of more violence. We might be looking at a Libya situation emerging in Yemen."
The U.S. State Department said its ability to help U.S. citizens in a crisis could be restricted, and that evacuation options would be "extremely limited" due to a lack of infrastructure, geography and security concerns.
It authorized the voluntary departure of the family members of U.S. embassy staff and non-essential personnel.
"The U.S. government remains concerned about possible attacks against U.S. citizens, facilities, businesses, and perceived U.S. and Western interests," the U.S. statement said, adding that al Qaeda's Yemen-based arm continued to be active in Yemen.
Yemeni protests, relatively peaceful in recent days, turned to violence in the town of Ibb when Saleh loyalists marched on an anti-government protest site where thousands were camped out, attacking anti-government demonstrators with stones and batons.
At least 36 people were injured, six critically, including a leader of the youth protest movement, a protest leader and witnesses said. Clashes were continuing.
Protesters say they are frustrated with corruption and soaring unemployment in Yemen where 40 percent of its 23 million people live on $2 a day or less and a third face chronic hunger.
Elsewhere in Yemen, gunmen shot dead a high ranking intelligence officer in a marketplace in the southern town of Zinjibar, a local official said. The officer, Abdel-Hamid al-Sherbani, was one of around 50 security officers thought to be on an al Qaeda hit list.
In the province of Maarib, east of the capital Sanaa, suspected al Qaeda militants killed four police officers in a shooting ambush, a local official said. The police vehicle had been delivering supplies to forces in the city of Maarib when the attack occurred.
(Additional reporting by Mohammed Ghobari in Sanaa and Mohammed Mukhashaf in Aden; Writing by Cynthia Johnston; Editing by Elizabeth Fullerton)