Australian author Harry Nicolaides, who had been imprisoned in Thailand for lese majeste, was granted a royal pardon on 19 February, media reports said.

"The Nation" online quoted the 41-year-old author's lawyer as saying that Nicolaides had boarded a flight to Australia and was expected to arrive in Melbourne today.

Nicolaides, arrested in August last year, was sentenced to three years' imprisonment last month for defaming the crown prince in his self-published book, "Verisimilitude".

"The Australian and Thai governments have been working together very closely on the resolution of Harry's case," lawyer Mark Dean said.

The ABC News online quoted the lawyer as saying, "The various steps that had to be taken in Thailand have been expedited in this case, resulting in the King being able to grant the pardon last Thursday."

Lese majeste is a criminal offense in Thailand, with a 15-year prison term.