Malaysian police said severed pigs' heads were found at two mosques on Wednesday, in the latest of a spate of attacks on places of worship that have escalated ethnic tensions.
The dumping of the heads of three pigs -- considered unclean by Muslims -- comes amid a row over the use of the word "Allah" by non-Muslims that has seen violence against 11 churches, a mosque and two Muslim prayer halls.
Police and religious leaders called for calm and said that saboteurs may be attempting to stir up ethnic conflict in Malaysia, a predominantly Muslim Malay nation which has large ethnic Chinese and Indian minorities.
"By looking at the modus operandi of the (pigs' head) incidents... I think it is the same group that is involved in the previous attacks," national police chief Musa Hassan told reporters.
"I think they are throwing money (to those carrying out the attacks) to cause such incidents," he said, warning those responsible not to "play with fire" and undermine national security.
The places of worship have been pelted with Molotov cocktails, stones and paint in tensions triggered by a December 31 court ruling that overturned a ban on non-Muslims using the word "Allah" as a translation for "God".
Nineteen people have so far been arrested for their roles in the attacks.
The government argues that the use of the disputed word by Christians, who make up nine percent of the population, could cause confusion and encourage religious conversion, which is illegal for Malaysian Muslims.
The severed heads, discovered in the grounds of two mosques in suburban Kuala Lumpur, were from wild pigs commonly found in Malaysia.
Zulkifli Mohamad, the imam who leads prayers at the Al Imam al Tirmizi mosque where two heads were found, called for calm and said Muslim saboteurs could be behind the latest incidents.
"This is the work of some people to stir racial tension in the country. We are shocked by their actions," he told reporters.
"I want the police to act fast, we ask Muslims to be patient, there is a possibility Muslims could be behind this incident."
Local parliamentarian Nurul Izzah Anwar, the 29-year-old daughter of opposition leader Anwar Ibrahim, also said she suspected the pigs' head incident was orchestrated by troublemakers.
"We are outraged by these attacks, it could be the act of saboteurs to destroy peace and racial harmony," she said at the scene.
"This area is a predominantly mixed area. On the ground, race relations are fine."
Religion and language are sensitive issues in multi-racial Malaysia, which experienced deadly race riots in 1969.
The population is 60 percent Muslim Malay, but also includes indigenous tribes as well as large ethnic Chinese and Indian communities -- practising Buddhism, Christianity and Hinduism, among others.
The row over the use of "Allah" is among a string of religious disputes that have erupted in recent years, straining relations between Malays and minorities who fear the country is being "Islamised."
The High Court last month ruled in favour of the Catholic Herald newspaper which has used "Allah" as a translation for "God" in its Malay-language section. The ruling was suspended pending an appeal.
Malaysia's Christians argue they have used the disputed word for centuries, in prayer and in translations of the Bible, and that the ban was an erosion of their rights.