Two Turkish nationals arrested in Malaysia are being held on suspicion of funding the Islamic State group, Kuala Lumpur said Thursday, after a rights organisation raised concerns of pressure from Ankara for the detentions.

Malaysia's anti-terrorism police unit had been investigating the two men, along with a number of others, for "spreading, influencing and funding" IS activities, deputy prime minister Ahmad Zahid Hamidi said.

Officers had a raft of communications between Turgay Karaman and Ihsan Aslan, Zahid told reporters, without revealing details of the alleged exchanges.

News of the arrests broke Wednesday, when national police chief Khalid Abu Bakar tweeted that the men were being held "because they threatened the security of Malaysia."

But Turkey's state-run news agency said that the pair were linked to a US-based preacher accused of organising a failed coup last year.

Karaman and Aslan were being held under the Security Offences (Special Measures) Act, the deputy prime minister added, which allows police to detain them for 28 days.

Suspects are often only allowed access to lawyers once they are charged in court.

Phil Robertson, deputy Asia director at Human Rights Watch, on Wednesday said Malaysia should not become "a handmaiden to Turkish repression".

"The Turkish government is on a witch hunt against the perceived enemies of President Erdogan," he said.

But on Thursday Malaysian police chief Khalid said there had been no request from the Turkish government to detain the men.

He did not respond to questions about whether the pair would be deported.

"There was no request from anyone. It (the arrest) is due to their own doing," he said.

Zahid, however, said Kuala Lumpur would collaborate with the Turkish police and military intelligence with regards to the arrests.

The wives of the duo have denied the allegations.

"They have never hurt anyone," Ayse Gul Karaman, wife of Karaman, was quoted as saying by the Star newspaper Thursday.

President Erdogan's government has detained or sacked tens of thousands of people under a state of emergency imposed after last year's failed coup.

The crackdown focuses on alleged supporters of preacher Fethullah Gulen, blamed for the failed putsch.