Ayidh Al-Shabwani is listed as the most dangerous Al-Qaeda operative in Yemen who survived many airstrikes on his fiefdom in Mareb. He is blamed for orchestrating many attacks that targeted security forces in the area.
Ayidh Al-Shabwani was killed 4 km east of Zinjibar, a government source said.
Medical sources said 10 soldiers had been killed and 33 wounded in the operation near Zinjibar.
Reuters news agency quoted Deputy Information Minister Abdo Al-Janadi as saying that the United States provided logistical support to the 25th Mechanized Brigade, which has been besieged by militants in Zinjibar since late May.
"The American forces are helping Yemen in its fight against Al-Qaeda" with material support, Al-Janadi said. "They helped the army by bringing in food supplies when they were besieged by Al-Qaeda members," he added, responding to a question during a Sanaa news conference about alleged American involvement in Zinjibar.
An official in Abyan said ships and boats believed to be American were seen in the area of Zinjibar. He also said there had been killings by snipers in the city during the night, which would have required night-vision equipment.
The ministry said Abdul Rahman Mohammed Dao'an, another Al-Qaeda commander, was arrested in Abyan's Lowder district. Dao'an was on a government list of most wanted men and believed responsible for setting an ambush that killed 10 soldiers in Abyan on June 6.
Ahmed Al-Kuhlani, the head of the government's relief operations, said the number of people displaced by the ongoing fighting in Abyan has increased to 90,000, or close to 13,000 families. They are being sheltered in Aden and Lahj. Al-Kuhlani expected the number to increase and appealed for international help to cope with the problem.
In violence elsewhere, a protester was shot dead Thursday in Taiz city when government forces opened fire on an anti-regime rally. The rally was taken out to condemn Wednesday's attack in Sanaa on Islah party chief Mohammed Yadoumi.
Fighting between the Republican Guards and armed men killed two people in Arhab, which has been the scene of shelling and gunbattles in the past three days. It was not known whether those killed had taken part in the fighting or had been hit in the crossfire.
In the capital, 20 opposition blocs announced the formation of a revolutionary council that would seek President Ali Abdullah Saleh's ouster. The new council was the third anti-regime coalition formed in a week.
Yemen's opposition coalition said Wednesday it would form a "national coalition council," to bring together the Common Forum parliamentary opposition parties, young protesters and the Southern Movement.
Earlier this week, the Youth Council of the Yemeni revolution declared a 17-member council to run the country.
