MINSK, Belarus — Authorities expelled two U.S. citizens for what they said was "illegal missionary activity," the Belorussian security agency said Monday.

The two were identified as members of The Church of Jesus Christ of Latter-day Saints who came to work with an international humanitarian organization called "Sofia" in the eastern Belorussian town of Mogiliyev, said the security service, known by its acronym, KGB. Their names were not given.

The KGB said the two were expelled because they were conducting "illegal missionary activity" and because the church was not registered in the Mogiliyev region.

"The U.S. citizens were involved in disseminating Mormon religious teachings among the population, conducting meetings, handing out literature," the KGB said.

LDS Church spokesman Michael Otterson said that the church is looking into the incident. "The church has several humanitarian aid workers in Belarus. In Belarus and in all other countries," he added, "the church teaches its members and representatives to live and act with respect for the law wherever they work or reside."

Two years ago, President Alexander Lukashenko pushed through what many critics call the most restrictive religion law in Europe. The law bans organized prayer by religious communities of fewer than 20 members and prohibits religions that have been represented in Belarus for less than 20 years from publishing literature or setting up missions.

Passage of the law appeared to be an attempt to end the inroads minority religions, especially evangelical Protestants, have made in Belarus, where opinion polls indicate that 80 percent of the population consider themselves Orthodox.

In January last year, a Minsk court warned the presbyter of the Renaissance Baptist Community after holding a prayer meeting with 70 worshippers in his home. And in June 2003, a Pentecostalist preacher was fined $35 for holding a prayer meeting in a village.