Several severed pigs' heads have been found in mosque compounds in the Malaysian capital, Kuala Lumpur.
The national police chief, Musa Hassan, linked the discoveries to recent attacks on various houses of worship.
Pigs are considered unclean by Muslims and their presence in the mosque compound will be taken as an insult.
In recent weeks, 11 churches, one Sikh temple and some Muslim prayer halls have been vandalised amid a row over non-Muslims' use of the word Allah.
Religious tensions in Malaysia have increased since a court ruled last month that a Roman Catholic newspaper could use the word Allah in its Malay-language edition to describe the Christian God.
Home Minister Hishammuddin Hussein said the people behind the latest incident would be brought to justice.
"The majority of Malaysians are peace-loving people, the majority of Malaysians would not do this act," the AFP news agency quoted him as saying.
AFP reported the police chief as saying he believed the attacks were being funded by a group that was attempting to worsen tensions in Malaysia, a predominantly Muslim nation which is also home to large ethnic Chinese and Indian communities.
"By looking at the modus operandi of the two incidents... I think it is the same group that is involved in the previous attacks," he told reporters.
"I think they are throwing money [to those carrying out the attacks] to cause such incidents."
He added: "Don't play with fire, I will not compromise on the security of the country. Please do not provoke the public or any parties to undermine the security of the country."
At least one severed pig's head was found at the Taman Dato Harun mosque in a nearby district, said the mosque's prayer leader, Hazelaihi Abdullah.
The police chief confirmed this incident and said two others were left at the nearby Al Imam al Tirmizi mosque.
Separately, Zulkifli Mohamad, the top official at the Sri Sentosa Mosque on the outskirts of Kuala Lumpur, said men arriving for early morning prayers found two bloodied pigs' heads in plastic bags in the compound.
"We feel this is an evil attempt by some people to aggravate tensions," Mr Zulkifli told The Associated Press.
No-one has been hurt in the series of attacks on various houses of worship since the 31 December court ruling which allowed non-Muslims to use the word Allah as a translation for God.
Police have arrested 19 people in connection with the attacks so far.
Correspondents say some of Malaysia's majority Muslim community suspect Christians of wanting to use the word Allah to encourage Muslims to convert to Christianity.
Analysts say the controversy has been stoked by hard-line elements within Malay Muslim political groups to assert Malay primacy in a shifting political scene.
The government has appealed against the ruling, in contrast to countries such as Indonesia, Egypt and Syria where Christian minorities freely use the Arabic word to refer to God.