Converts moving up in terrorist organizations....

A disturbing trend, for sure...

Religious converts are playing an increasingly influential role in Islamic militant networks, having transformed themselves in recent years from curiosities to key players in terrorist cells in Europe, according to counterterrorism officials and analysts.

The arrests this month of two German converts to Islam -- Fritz Gelowicz and Daniel Schneider -- on suspicions that they were plotting to bomb American targets are just one example of terrorism cases in Europe in which converts to Islam have figured prominently.

In Copenhagen, a convert is among four defendants who went on trial this month for plotting to blow up political targets. In Sweden, a webmaster who changed his name from Ralf Wadman to Abu Usama el-Swede was arrested last year on suspicion of recruiting fighters on the Internet. In Britain, three converts -- including the son of a British politician -- are awaiting trial on charges of participating in last year's transatlantic airline plot.

"The number of converts, it seems, is definitely on the rise," said Michael Taarnby, a terrorism researcher at the Danish Institute for International Studies. "We've reached a point where I think al-Qaeda and other groups recognize the value of converts, not just from an operational viewpoint but from a cultural one as well."

Religious converts are sometimes more prone to radicalization because of their zeal to prove their newfound faith, analysts said. They are also less likely to attract police scrutiny in Europe, where investigators often rely on outdated demographic profiles in terrorism cases.

Converts are a tiny subset of the Muslim population in Europe, but their numbers are growing in some countries. In Germany, government officials estimated that 4,000 people converted to Islam last year, compared with an annual average of 300 in the late 1990s. Less than 1 percent of Germany's 3.3 million Muslims are converts.

While religious leaders emphasize that most converts are law-abiding citizens who often promote interfaith understanding, the recent arrests in Germany prompted some lawmakers to suggest that police should keep converts under surveillance.

"Of course not all converts are problematic, but some are particularly dangerous because they want to demonstrate through extreme fanaticism that they are particularly good Muslims," Guenther Beckstein, interior minister for the state of Bavaria, said last week.

The trend is not limited to Europe. In Florida, U.S. citizen and convert Jose Padilla was convicted last month on conspiracy charges for participating in an al-Qaeda support cell. In March, David M. Hicks, an Australian convert, became the first prisoner at the U.S. prison at Guantanamo Bay, Cuba, to be convicted on terrorism charges.

Converts have joined militant groups, including al-Qaeda, for years. Wadih el-Hage, a Lebanese Christian who converted to Islam and became a U.S. citizen, served as an aide to al-Qaeda leader Osama bin Laden in the 1990s and was convicted for his role in the 1998 U.S. embassy bombings in East Africa.