Updated

A suspected U.S. drone aircraft fired a missile at a car in southern Yemen on Thursday, killing two brothers believed to be al-Qaida militants, said security and tribal officials.

Yemen's Defense Ministry confirmed the deaths of the brothers in Shabwa province, but would not provide any further details.

In September, the country's foreign minister said it was no longer allowing missile strikes by pilotless planes. But after al-Qaida smuggled explosives aboard cargo planes bound for the U.S. in late October, it is believed the strikes resumed.

Yemen, which is wracked by massive protests against the country's deeply unpopular president, is also home to one of the most active branches of al-Qaida, which has planned several attacks against the U.S.

Shabwa provincial security and tribal officials reached by telephone identified the two brothers as Abdullah and Mosaad Mubarak, but they did not explain why they were sure the attacks were carried out by pilotless aircraft.

The officials spoke on condition of anonymity because of the sensitivity of the incident.

Al-Qaida in the Arabian Peninsula, as the local branch calls itself, is estimated to number around 300 fighters with built up strongholds in the provinces of Shabwa, Abyan, Jouf and Marib, regions of daunting mountain ranges where central authority has nearly no presence.

In addition to attacking government targets, the group has inspired attacks by Muslims inside the United States and twice smuggled explosives aboard aircraft headed to America.

The U.S. originally carried out a campaign of drone strikes similar to the one that killed many al-Qaida figures in Pakistan until a local official was accidentally killed. In September, Foreign Minister Abu Bakr al-Qirbi said the strikes had been suspended.

The U.S. has poured money into training Yemeni counter-terrorism forces with $150 million in annual military assistance and up to 100 trainers at any given time.

The popular protests calling for the ouster of long-serving President Ali Abdullah Saleh across the country, however, have disrupted government efforts against al-Qaida.

On Thursday, thousands of protesters again hit the streets to demand that Saleh step down, marching in the south and central Yemen. In at least two of the protests, Saleh supporters attacked marchers.

In the central city of Bayda, activists said supporters of Saleh burned some tents in a protest camp in the city's square as protesters prayed.

Hundreds more protesters arrived at the camp to denounce the burning as others collected donations to replace the tents, said an activist who spoke on condition of anonymity because he feared reprisals.

"We will rebuild," the protesters shouted.

In the town of Damt, in the southern province of al-Daleh, supporters of Saleh organized a march in his support, waving automatic rifles and sticks. The crowd stormed a record store, beating its owner for playing anti-Saleh songs, said Mohammed al-Marfadi, a local activist.

They also attacked an ice cream vendor who had wrapped his head in a national flag with the word "go" scribbled over it.