The Malaysian authorities have arrested 19 suspected terrorists, including eight Abu Sayyaf militants, in a series of swoops across four states in the past few weeks.

The suspects comprise eight Malaysians and 11 foreigners. The foreigners are from Bangladesh, the Maldives, Iraq, Palestine, the Philippines and Indonesia.

They were nabbed by the Special Branch Counter-Terrorism Division in Selangor, Kuala Lumpur, Kelantan and Johor between July 4 and Aug 30.

Their arrests added to the more than 260 Malaysians and foreigners who have been put behind bars by the authorities since 2013, as South-east Asia's third-biggest economy battles supporters and sympathisers of the Islamic State in Iraq and Syria (ISIS) and affiliates of the terror organisation.

Those who had been arrested in the past included Malaysians who were army personnel and policemen, and women who wanted to travel to Syria to join ISIS.

Malaysia is a magnet for tens of thousands of students from Muslim countries and about two million migrant workers seeking higher pay, and some of them have been among those arrested in recent years.

On the latest arrests, Malaysia's newly appointed police chief Mohamad Fuzi Harun said two of the suspects had planned to launch attacks during the closing ceremony of the 29th SEA Games at Bukit Jalil Stadium and Malaysia's National Day celebration on Aug 31 at Dataran Merdeka, a public square in Kuala Lumpur.

In the first raid, a 25-year-old Bangladeshi man who worked as a temporary teacher at a religious school in Gombak, Selangor, was arrested on July 4.

He is suspected to be a member of Jamatul Mujahideen Bangladesh, an ISIS affiliate.

Datuk Seri Mohamad Fuzi said others hauled in by the police included two men - a Palestinian and an Iraqi - on Aug 15 and Aug 16 in Kuala Lumpur and Selangor.

Police also arrested eight members of the Abu Sayyaf group - two Philippine nationals and six Malaysians.

Their arrests were conducted with the help of Malaysia's elite Special Action Unit on Aug 30.

Mr Mohamad Fuzi said the mastermind of the Abu Sayyaf group, a 25-year-old man, had sneaked into Sandakan, Sabah, before heading to Kuala Lumpur in December 2015.

He added that the man had planned to launch attacks during the closing of the SEA Games and the National Day celebration.