SANAA (Reuters) - Yemen's opposition accused the government on Friday of killing dozens of civilians, including whole families, in raids a day earlier which the authorities said had killed about 30 al Qaeda militants.

Yemen said on Thursday that security forces and warplanes had foiled a planned series of suicide bombings by attacking targets including an al Qaeda training center in the southern province of Abyan and sites in Arhab district.

The troops killed 30 al Qaeda militants and arrested 17 in Abyan and in Arhab, northeast of the capital Sanaa, it said.

U.S. President Barack Obama called Yemeni President Ali Abdullah Saleh, saying the operation "confirms Yemen's resolve in confronting the danger of terrorism represented by al Qaeda for Yemen and the world," Yemen's state media said.

An opposition website quoted sources in Abyan as saying 18 children and 41 men and women were killed in the attack there, eight families losing four to seven members each.

"In a dangerous precedent, ... the Sanaa regime committed a brutal massacre against our people," exiled southern leader Ali Salem al-Beidh said in a statement, calling for an investigation by the United Nations, and by Arab and Muslim countries.

A government official accused Beidh, who lives in Germany, of supporting al Qaeda in his statement and called for him to be handed over to Yemen, the state news agency Saba said.

As well as fighting al Qaeda militants, Yemen, the Arab world's poorest country, is battling separatist unrest in the south and a separate Shi'ite rebellion in the north.

Analysts say such conflicts, along with falling oil income, water shortages and a humanitarian crisis, add to instability in a region that includes oil superpower Saudi Arabia and one of the world's busiest shipping lanes.

MP Ali Ashal from the Islamist opposition Islah party called for a parliamentary investigation into the raids.

"We are surprised by this operation, which shows the extreme foolishness of those who ordered it, because they ordered the shedding of innocent blood," Ashal told an opposition website.

Yemen joined the U.S. war on terror after the Sept 11, 2001 attacks on U.S. cities.

The conflict in northern Yemen drew in Saudi Arabia last month when the rebels briefly occupied some Saudi territory, prompting Riyadh to launch an offensive against them. The rebels accuse Riyadh of backing Sanaa militarily since the war started.

Saudi Arabia fears instability in Yemen could turn into a security threat for the kingdom by allowing al Qaeda to gain a stronger foothold in its fragile neighbor.

More than 74,000 Africans have fled to Yemen this year, a 50 percent increase from 2008 despite the country's instability, according to figures issued on Friday by the Office of the U.N. High Commissioner for Refugees in Geneva.

(Writing by Firouz Sedarat in Dubai, editing by Tim Pearce)

www.nytimes.com/reuters/2009/12/18/world/international-us-yemen-raids-casualties.html