Malaysia has detained seven militants suspected of planning attacks in the country, in several raids in Johor and Sabah.

Members of a clandestine terror cell, which included two men working as janitors in Singapore, were planning to kidnap and kill policemen and attack non-Muslim houses of worship, police said in a statement yesterday (March 24).

The plot was uncovered after Malaysian counter-terrorism police, aided by their Singaporean counterparts, detained the terror suspects in a series of swoops between Feb 27 and March 15.

The order to kidnap and kill policemen was the first of its kind, according to an intelligence source.

"This cell is extremely cautious... they are vengeful against the police, especially those from E8 (counter terrorism)," an intelligence source told The Straits Times.

In a statement yesterday, Malaysia's police chief Mohamad Fuzi Harun said six suspects who were detained in Johor were members of an Islamic State in Iraq and Syria (ISIS) cell.

In the first round of arrests on Feb 27, three men were nabbed, with the main suspect being a 37-year-old technician who masterminded the plans to attack places of worship in Johor Baru. He was also actively recruiting new militants.

Police picked up another three members of the same cell in follow-up sweeps on Feb 28.

He said: "The fourth suspect, a 25-year-old waiter, had been ordered by the mastermind to kidnap and kill policemen.

"Two others, aged 23 and 22, were arrested on March 1 and worked as janitors in Singapore. "

According to a Malaysian intelligence source, the two were arrested by Singaporean counterparts before they were handed over to the Malaysian police.

"Singapore was informed of the duo's alleged involvement in terrorism by Malaysia. They then tracked down and arrested the men before handing them over to the authorities here," the source said.

The seventh suspect was a 31-year-old, said to be a "trusted lieutenant" in the Abu Sayyaf group in the Philippines. He was detained in Sabah on March 15.

"The Filipino man is a trusted lieutenant to Furuji Indama, the group's leader based in Basilan.

"We believe the suspect has connections to Malaysian militant, Dr Mahmud Ahmad, and is also wanted by the Philippine authorities for involvement in a kidnap-for-ransom syndicate. He is an expert in making improvised explosive devices and had planned to attack several locations in Sabah," Mr Fuzi said.

Malaysia has arrested nearly 400 people since 2013 for suspected links to terrorism.

The Muslim-majority nation faces threats from self-radicalised ISIS sympathisers at home, and regional militant groups which seek funding and refuge in South-east Asia.

The country's first and only terrorist attack took place in June 2016, when two men on a motorcycle lobbed a grenade into a nightclub in Selangor, injuring eight people. The men were sentenced to 25 years' jail.