BENGHAZI, Libya, Jan 19 (Reuters) - Libya's internationally-recognized government has recalled retired general Khalifa Haftar to army duty, officials said on Monday, cementing its alliance with him in a struggle against a rival administration claiming national authority. The decision shows the increasing influence of military figures in the official government and parliament, which has been forced to operate from the east of the country since an armed group called Libya Dawn seized the capital Tripoli in summer. Frustrated with the loss of Tripoli and lack of an efficient army or police, the elected parliament and its allied Prime Minister Abdullah al-Thinni have gradually built up a military alliance with Haftar. Haftar, a former general under Gaddafi, is one of dozens of commanders of irregular forces which have refused to disarm after the ousting of Muammar Gaddafi in 2011. In May he launched his own war against Islamist fighters in the eastern city Benghazi. But his warplanes have also attacked commercial airports and a steel plant in western Libya. They hit a Greek-operated fuel tanker in Derna this month, killing two seamen, after Haftar's forces claimed it was carrying Islamist fighters. A copy of an official decree obtained by Reuters recalled Haftar and 108 other former Gaddafi-era army officers for active army duty. Haftar's air force chief Saqer al-Joroushi and lawmaker Idris Abdullah confirmed the contents of the decree. It was issued weeks ago but had not previously been made public. Libya Dawn has denounced Haftar as a Gaddafi loyalist trying to stage a counter-revolution with former regime officials. Haftar helped Gaddafi seize power in 1969 but fell out with him in the 1980s after a disastrous defeat during a war in Chad. Haftar has said he only wants to rid Libya of Islamist groups such as Ansar al-Sharia, blamed by Washington for a 2012 assault on the U.S. consulate which killed its ambassador. In a video message in February he announced what some feared was a coup, though that did not materialize. Later he demanded a special council to run Libya. Haftar has also drawn support from an armed group in the western town of Zintan which was blamed for an attack on parliament in Tripoli in May. Senior officers linkled to Haftar have also been given top posts in the recall. Libya Dawn says Haftar is supported by Egypt and the United Arab Emirates, which are worried about the spread of Islamists. He denies this but some analysts wonder how the tiny air force is able to stage almost daily attacks. (Reporting by Ayman al-Warfalli, Feras Bosalum and Ahmed Elumami; Writing by Ulf Laessing; Editing by Andrew Roche)