(Adds German foreign minister) KABUL, Aug 20 (Reuters) - Afghan security forces captured four men on Monday who kidnapped a female German aid worker at the weekend, a government spokesman said. The men belonged to a criminal gang and authorities are investigating whether the group has more members, Interior Ministry spokesman Zemarai Bashary told reporters. No shots were fired during the pre-dawn raid on a house in the rundown area of Kabul where Christina Barbara Meier was held, he said. Meier, who works for a Western aid agency, was seized by armed men from a restaurant in Kabul on Saturday. Her abduction was the first of a Westerner in the city in more than two years. German Foreign Minister Frank-Walter Steinmeier said Meier was in the custody of the German embassy in Kabul and the ambassador would be speaking to her later in the day. He praised the operation that freed her: "The timing was right as we have seen," he said in Berlin. He also thanked Norwegian security forces in Kabul for their contribution. Hours before the raid, Meier appeared in a video aired by a private television station to plead with Berlin to use all efforts to free her. A bespectacled man who had his face covered said on the video the abductors belonged to a special network and demanded the release of its members held by the Afghan government in return for freeing the German woman. Bashary said Afghan police last week also arrested the mastermind behind the killing of two German journalists last year in central Afghanistan. He declined to identify the man. The abduction of Meier came nearly a month after Taliban guerrillas kidnapped nearly 30 people, most of them foreigners from separate locations outside the capital. The Taliban have killed two of the 23 South Korean hostages the militants seized southwest of Kabul and released two of them. The group has also killed one of the two male German engineers it had separately seized. The Taliban are still holding the other German and four of his Afghan colleagues and have demanded the withdrawal of Germany's troops from Afghanistan in return for the German's freedom. Berlin has refused to do so. A number of foreigners have been abducted by criminal gangs in Kabul in the past, but have been freed after an apparent ransom payment.
