Eleven Islamist militants killed in southern Yemen ADEN (Reuters) - Yemen's army killed at least 11 al Qaeda-linked militants in Abyan province on Wednesday as it pressed ahead with a U.S.-backed offensive to crush Islamist militancy in the south, a military official said. The Ministry of Defense said in a text message that some of the dead militants had been senior military leaders in Ansar al-Sharia (Partisans of Islamic Law), a group which has close links to the Yemen-based al Qaeda in the Arabian Peninsula (AQAP). Earlier in the day, a Yemeni aid worker for the International Committee of the Red Cross (ICRC) was killed by an air strike while carrying out humanitarian work, the agency said. A local official told Reuters the Yemeni air force had conducted the strike that killed the ICRC worker, adding that the military had carried out at least three separate air strikes on Wednesday. He said the aid worker had been trying to contact al Qaeda militants in order to negotiate the release of a French co-worker who was kidnapped in April. Yemen is several weeks into a U.S.-backed offensive against militants who seized territory in the south last year during turmoil that forced President Ali Abdullah Saleh to step down. Earlier this month, the army drove al-Qaeda-linked fighters from two of their main strongholds after weeks of fighting. Reporting by Mohammed Mukhashaf; Writing by Mahmoud Habboush; Editing by Kevin Liffey and Andrew Osborn