(Adds local security official, background)
By Mohamed Mukhashaf
ADEN, Yemen, April 20 (Reuters) - A number of al Qaeda militants were killed when an air strike hit their training camps in a remote mountainous region of southern Yemen on Sunday, the defence ministry said, the second attack of its kind in two days. On Saturday an air strike killed 10 al Qaeda militants and three civilians in central Yemen, a country that neighbours top oil exporter Saudi Arabia and is home to al Qaeda in the Arabian Peninsula (AQAP), one of the group's most lethal wings.
Yemen's defence ministry website quoted an official source on the High Security Committee as saying that an air strike hit the mountainous region between al-Mahfad in Abyan province and Azzan in Shabwa after information that "terrorist elements were planning to target vital civilian and military installations".
The source did not say exactly how many people had been killed, but a local official told Reuters three suspected al Qaeda militants had died in the strike on al-Mahfad. He did not know how many people had died in the Shabwa attack.
The source said the militants targeted were among the "leading and dangerous" elements of al Qaeda and were of different nationalities.
Riyadh also watches AQAP with concern since the branch was founded by citizens of both countries and has sworn to bring down its ruling al-Saud family.
An online video has been circulating with AQAP leader Nasser al-Wuhaishi addressing a large gathering of fighters in an undisclosed mountainous region of Yemen and vowed to attack the United States.
The exact nature of the strikes were unclear. The United States has stepped up drone strikes as part of a campaign against the Yemen-based AQAP. Yemen is among a handful of countries where the United States acknowledges using drones, but it does not comment on the practice.
U.S. drone attacks have killed several suspected AQAP figures, including Anwar al-Awlaki, a U.S.-born Islamist cleric accused of links to a plot to bomb a Detroit-bound airliner in 2009 and U.S. cargo planes in 2010.
Yemen has been fighting AQAP but the group, which has attacked military targets, tourists and diplomats in the country and taken over territory for long periods, is proving hard to beat so far. (Reporting by Mohamed Mukhashaf; Writing by Yara Bayoumy; Editing by Hugh Lawson)