Xavier Andre Justo, the Swiss national accused of attempting to blackmail his former employee PetroSaudi International, is allowed to have visitors.

He has many visitors besides his lawyers, and the visitation does not involve the police, said Thai Police chief Somyot Poompanmoung.

Somyot said the lawyer had the right to bring anyone to visit Justo. "Thus a reporter may have access to Justo through his lawyer," he added when asked how Singapore's The Straits Times was able to interview Justo recently while the Malaysian police could not.

"I don't know about this (The Straits Times interview), but if the media went there, they must have gone with the suspect's lawyer, and the police were not involved," he said.

He said the Malaysian police was denied access to Justo as he was not a Malaysian citizen and did not commit an offense in Malaysia.

The Malaysian police had to go through the proper channel - through the Foreign Ministry - to interrogate Justo, Somyot said.

He said he informed Inspector general of police Tan Sri Khalid Abu Bakar on July 23 that based on his initial look at the situation, it was unlikely for the Malaysian police to be allowed to interrogate Justo.

"If the Thai government or police allow the Malaysian police to interrogate Justo then we could be criticised by the Swiss embassy," he added.

As for when Justo will be charged in the court, Somyot said this depended on the investigation officers.

Justo has been in custody in Thailand since June 22.