(CNN) -- Authorities in Malaysia have seized more than 20,000 Bibles in recent months because they refer to God as "Allah," Christian leaders said Thursday.

The seizures have fed fears among minority groups, which see signs of encroaching Islamic fundamentalism in the predominantly Muslim but multi-racial country.

"There is a growing sense of Islamic assertion, yes," said the Rev. Hermen Shastri, general-secretary of the Council of Churches of Malaysia. "There is some concern."

The Bibles were written in the country's official language, Malay -- in which the word for God is "Allah," as it is in Arabic.

However, Malaysia's government says the word is exclusive to Islam.

Its use in Christian publications is likely to confuse Muslims and draw them to Christianity, the government says. So it has banned use of the word in Christian literature.

"Malay has borrowed from Arabic, just as it has from Sanskrit and Portuguese," Shastri said. "We have maintained the community has the right to use the word.

"But I think this has ignited a cause in the Muslim communities, who are interpreting it as a siege on Islamic beliefs."

A Home Ministry official directed requests for comment to the ministry's Publications and Quran Text Control Department, which enforces the ban. An employee there redirected calls to a spokeswoman, who in turn asked CNN to call the Home Ministry back. Calls to other departments were similarly redirected.

A Roman Catholic weekly newspaper, The Herald, is challenging the ban in court after the government threatened to revoke its license for using the word in its Malay edition. Hearings on the case have gone on for two years.

"We quote it as it is. We cannot change the text of the Scripture," Herald editor Father Lawrence Andrew told CNN last year. "I cannot be the editor of the Bible."

Among the Bibles confiscated were Malay-language ones that the Bible Society of Malaysia said it had imported from Indonesia. About 10,000 others also were confiscated from Gideons International, which places free copies in hotel rooms and other places.

The Malaysian constitution provides for freedom of religion. The country has a dual-track justice system, in which Islamic courts operate alongside civil ones.

Rulings by the Islamic, or sharia, courts are directed toward the country's Muslim, who make up 60 percent of the population. But they worry non-Muslims who see them as Islamism seeping into the moderate nation's fabric.

In November, the National Fatwa Council -- the country's top Islamic body -- banned Muslims from practicing yoga. It said elements of Hinduism in yoga can corrupt Muslims.

The council also bans short hair and boyish behavior for girls, saying they encourage homosexuality.

In northern Malaysia's Kelantan state, authorities have forbidden bright lipstick and high-heeled shoes, saying the bans will safeguard Muslim women's morals and dignity, as well as thwart rape.

And last month, an Islamic court judge in the eastern state of Pahang upheld a verdict to cane a Muslim woman for drinking beer in public.

The country has been mired in inter-faith disputes as well in recent months. In those cases, many non-Muslims complain that the civil courts generally cede control to Islamic courts.

Muslims cannot convert to other religions without the permission of the Islamic courts, which rarely approve such requests.

In relationships in which a Muslim parent has converted children to Islam over the objection of a non-Muslim parent, the sharia courts usually have upheld the conversions.

And earlier this year, a Sikh family lost a court battle to cremate a relative after officials said the man had converted to Islam years before his death, though the family said he hadn't.