A human rights groups expressed concern over the displacement of "a shocking number of people" during fighting in south Yemen and warned against any disproportionate offensive against suspected al Qaeda fighters.
Yemen's Red Crescent said this week that up to 12,000 civilians had been forced to flee clashes between suspected al Qaeda militants and government forces in and around the town of al-Hota in the southern province of Shabwa.
Amnesty International said some inhabitants of al-Hota had told the rights watchdog that the suspected militants were in fact armed tribesmen with grievances against the government.
"The nature of the assault may be -- for a law-enforcement operation -- grossly disproportionate," Amnesty said in a statement on Wednesday.
The Yemeni government has confirmed that civilians had been asked to move out of the area to avoid being caught up in military operations.
"Residents were advised to evacuate their homes to minimise collateral damage," a spokesman for the Yemeni embassy in Washington said in a statement late on Wednesday.
Across southern Yemen, thousands marched on Thursday in support of a call by separatists for a donors' meeting in New York on Friday to consider the plight of the south, residents said.
Impoverished Yemen has faced increasing unrest by southern separatists who say the northern-based government has discriminated against them and exploited their region's resources. The government denies the accusation.
The military assault on Hota was a response to a recent attempt by suspected militants to bomb a key gas pipeline running to an export point in Shabwa, the $4.5 billion Total-led (TOTF.PA: Quote) liquefied natural gas (LNG) plant that started production in October, it said.
Amnesty International urged the Yemeni government to protect those displaced by the fighting.
"Whatever the nature of the ongoing operations, the Yemeni authorities must ensure as a matter of urgency that what amounts to a shocking number of people displaced in the space of a few days are adequately provided for," Philip Luther, Amnesty International's deputy director for the Middle East and North Africa, said in the statement.