Sri Lanka's The Island newspaper reported that Australia's high commissioner (ambassador) to Colombo had expressed concern about Gunaratnam's disappearance who was said to have Australian nationality.
Sri Lankan authorities have asked for details of his passport and the date of arrival to prove his presence in the country, the newspaper said.
Gunaratnam's mother had also called a media conference yesterday and pleaded for his release.
Opposition leader Ranil Wickremesinghe who also expressed concern over the disappearances said 56 people had disappeared so far this year, including political activists, political leaders and journalists.An Australian media report said Gunaratnam's wife had pleaded for his release from Australia. On January 03, she and her two children had been detained at the airport for questioning.