Police have confirmed the arrest of third Turkish national for allegedly "threatening public safety and order".

Inspector-general of police Khalid Abu Bakar said the man, in his 40s, who is on trial for allegedly assaulting an immigration officer, was arrested at a petrol station in Chenor, Pahang, yesterday.

On Wednesday, the top cop confirmed that two Turkish men - feared to be abducted at first - were actually detained under Section 130 of the Penal Code for activities that threaten national security.

Deputy Prime Minister Ahmad Zahid Hamidi said the two were being probed over links to the Islamic State (IS) terror group.

Khalid said the trio knew one another, but refused to say on whether they were linked to IS.

Asked how long they had been involved in terror activities, Khalid replied: "They had started to get involved, that is why we took action."

The IGP added that police had gathered sufficient information to act on the trio.

He said more arrests were possible but refused to go into specifics.

"If I say it, then they'll run away," he said.

Khalid also rubbished notions that the three were arrested on request of the Turkish government, saying Malaysia had a right to take action to ensure its security.

The Turkish government is alleged to have engaged foreign countries to help catch dissidents abroad.

Some of these dissidents are alleged to have links with exiled Turkish preacher Fetullah Gulen.

Khalid did not appear to know who Gulen was when asked if the trio had links with the exiled leader.

Human Rights Watch has urged the authorities to allow the detained Turkish nationals immediate and full access to legal counsel and their families.

"Malaysian authorities should explain why they are holding two long-time residents of Malaysia without charge on security grounds.

"Malaysia’s administrative detention laws open the doors to easy abuse, so it’s important for the government to provide the men’s location and to allow them immediate access to their families and legal counsel," its deputy Asia director Phil Robertson said in a statement.

The authorities should release the men from custody if they have not been charged with a credible offence, Robertson added.