A week after jailing eight foreigners on charges of propagating Christianity, the ruling Taliban militia on Sunday said they suspect a larger conspiracy by Western aid organizations to convert Afghan Muslims.

Taliban investigators have uncovered considerable evidence of large-scale conversion attempts and want to question other foreign aid groups, including the U.N. World Food Program, Taliban Foreign Minister Wakil Ahmed Muttawakil told reporters in the Afghan capital.

"Unfortunately some organizations under the guise of helping poor Afghans are preaching Christianity," Muttawakil said.

"The investigators are looking at a larger conspiracy by countries and organizations to try to convert good Afghan Muslims to Christianity," he said.

The Taliban, who espouse a harsh brand of Islam that considers trying to convert Muslims a crime, arrested eight foreign workers and 16 Afghan staff with Shelter Now International on Aug. 5 for allegedly preaching Christianity. The group is part of a German-based Christian group called Vision for Asia.

Among those arrested were two American women, four Germans and two Australians.

Muttawakil on Sunday said that the detained foreigners would not be released until the investigation is completed and that diplomats will not be allowed to visit them.

"We will give visas to the diplomats if they want to meet Taliban officials, but if it is to see those in jail we will not give the visas," he said.

During the raid on the Shelter Now International office, Taliban officials say they seized compact discs, cassettes and literature containing stories about Christianity and the coming of Jesus Christ — all translated into local languages.

"Our evidence is strong and we will be asking other organizations what they know about activities to spread Christianity in Afghanistan," Muttawakil said.

He made particular reference to the U.N.'s World Food Program, or WFP, suggesting the food aid group knowingly gave food to Shelter Now International to distribute as a means of enticing Afghan Muslims to Christianity.

"The WFP should be ready to answer questions when our investigation is completed because they must have known what this organization was doing and that it was trying to convert Muslims," said Muttawakil. "Our investigators have questions for them."

A WFP spokesman, Francis Mwanza, said at the group's Rome headquarters that it "has no religious intentions whatsoever."

"Our concern is to deliver food to NGOs (non-governmental organizations) on the ground who can get the food to the people," he said.

The relationship between the United Nations and the Taliban, who control about 95 percent of Afghanistan, has been troubled in recent years. But it deteriorated further following the imposition of fresh U.N. sanctions against the Taliban in January.

The sanctions, which included an arms embargo against the Taliban but not against its northern-based opponents, were imposed to press the hard-line militia to close terrorist training camps and hand over Osama bin Laden, who is wanted in connection with the 1998 bombings of two U.S. Embassies in East Africa that killed 224 people.

"There are some who want to keep the war in Afghanistan going so their Christian missionaries can come to this country and preach Christianity," Muttawakil said.

At the time of the arrests, the Taliban also detained 64 young men who officials said were being taught Christianity by the aid workers. The youths were later released, but an unknown number of their elder male relatives have been detained for allowing their children to undergo Christian education, according to the state-run Bakhtar News Agency.

The Taliban have forbidden proselytizing, and all international aid organizations are warned against preaching religion. According to other aid workers, they all agreed to abide by the Taliban rules.

It was still not clear how the Taliban will rule on the 16 Afghan staff of Shelter Now International, who have been held in a separate, undisclosed location. The penalty for Afghans found guilty of proselytizing is death.

On Sunday, a state-run newspaper, Shariat, published an edict issued last month by the Taliban's reclusive leader, Mullah Mohammed Omar, ordering a 3- to 10-day jail terms then expulsion from the country for any foreigner found guilty of proselytizing.

According to the newspaper, Deputy Justice Minister Jalaluddin Shinwari assured U.N. special envoy Francesc Vendrell that the edict would be applied to foreigners charged with preaching Christianity.

However, he did not make specific reference to the eight jailed workers, and Muttawakil's comments Sunday suggested the eight would be held longer.

Shelter Now International operates several projects throughout Afghanistan providing humanitarian assistance and participating in reconstruction projects like rebuilding irrigation canals. All the projects have been shut down.