(CNN) -- Two suspected U.S. drone strikes killed seven al Qaeda militants and eight civilians in the southern part of Yemen on Tuesday, three Yemeni security officials said.
It was the latest of several U.S. strikes in Yemen, which is home to al Qaeda in the Arabian Peninsula, described by U.S. officials as the al Qaeda affiliate that poses the most serious threat to the United States.
At least seven civilians were injured in the Tuesday strikes, the officials said.
Across Yemen, at least 49 people were killed, including 31 militants, according to a security official. The dead also included eight civilians, five troops and five pro-government local resistance fighters, according to the official.
The United States has increased the pace of airstrikes in Yemen in the last few years. At least 24 of 31 such strikes conducted since 2002 have happened in the last two years, according to the Long War Journal, which analyzes how the U.S. conducts its fight against terrorism.
According to the security officials, one of Tuesday's strikes targeted a militant hideout in Jaar district, a militant stronghold. Another strike targeted a home believed to be harboring militants in the same district.
Three senior al Qaeda leaders were among those killed, the officials said.
Jaar district residents said civilians were killed after they rushed to the site of the first strike.
"Our lives are valueless in the eyes of our government, and that is why civilians are being killed without a crime," resident Ali Abu Abdullah said.
One of the security officials expressed regret for the civilian casualties and injuries.
"The targets of the raids were not the civilians, and we give our condolences to the families of those who lost a loved one," the official said.
U.S. and Saudi authorities recently foiled an al Qaeda plot based in Yemen to bomb a U.S.-bound airplane.
Elsewhere in Yemen, in Lowder district, at least 17 al Qaeda fighters were killed when tribesmen loyal to the government clashed with militants and took over three strategic locations in the district. Three security officers were killed in Lowder.
At least 400 tribal fighters backed by hundreds of troops participated in the Lowder raids.
Mohammed Aidaroos, a local leader, said the fighting erupted early Tuesday morning in Lowder, and government-supported fighters forced al Qaeda fighters to evacuate the area and leave behind huge caches of weapons.
The tribal fighters took back control of Yasoof Mountain, which al Qaeda had controlled for more than a month.
There was also a state of alert in the Yemeni capital.
The Interior Ministry warned on Tuesday that al Qaeda is planning to conduct suicide operations in Sanaa.
Tight security presence was noticeable near Western embassies and in the diplomatic zone of the capital.
"The ministry has been given intelligence information warning of a possible attack in the heart of the Yemeni capital and we are on high alert," one Interior Ministry official told CNN on condition of anonymity because he is not authorized to speak to the media.
Yemeni Information Minister Ali al-Amrani told CNN he was targeted Monday when a grenade was thrown near his home in Sanaa. The grenade landed about 100 meters from his home, al-Amrani said, and he was not injured.
In January, Al-Amrani escaped an assassination attempt unharmed when at least 10 shots were fired in the direction of a vehicle he was entering. Witnesses said there were at least two gunmen.
Al-Amrani's spokesman said following that attack in January that al-Amrani was being targeted in a hate campaign by pro-revolution groups.