Nukul Yongnoo, the manager of a local cable television station and a restaurant owner, said his meeting with Muang Phatthalung police was meant to demonstrate his innocence.
He said he was at a restaurant in Muang district at the time of the car bomb on the night of April 10. Police interviewed Nukul and registered him without charging him.
Meanwhile, PM General Prayut Chan-o-cha said he knew about a former deputy prime minister's alleged involvement in the attack "equally to what the media knew".
Prayut has cited the theory that politics may have had something to do with the bomb attack and other incidents, including a large fire at a cooperative in Surat Thani's Koh Samui.
He said insurgent attacks were usually simple and only involved a few steps, while evidence showed that the Samui blast was carried out in a more sophisticated manner, with many operatives to steal and create the vehicular bomb, including partly changing the car's colour.
Prayut called on the media and public not to jump to the conclusion that politics was behind the incident.
"There are many details detected in the investigation, and one of them happens to involve a person who is a former MP," he said, without elaborating.
Meanwhile, the military released a man yesterday who put a message on Facebook that suggested there would be strife in Surat Thani, several hours before the fire at the cooperative and the car-bomb blast.
National Council for Peace and Order spokesman Colonel Winthai Suvari said there was no solid evidence against Narin Amnongbua, whose Facebook name is M Redshirt, but he would be closely watched.
Army chief General Udomdej Sitabutr backed down from his earlier statement that politicians were behind the car-bomb attack.
He also ruled out that it was an expansion of the insurgency in the far South, although some equipment used in the attack matched what was used in the strife-torn region.
In related news, the mayor of Samui municipality, Ramnet Jaikwang, said the total number of surveillance cameras on the tourist island would soon reach 3,000 - more than double the current 1,300 units - 300 of which are operated by the municipality.
He said that authorities operating public transport services and the owners of relevant businesses would be invited to attend a meeting to work out joint security measures, including the inspection of vehicles going to and from the island.
An inspection of records of the 200,000 or so people staying and working on the island would also be carried out, he said, noting that the island has about 60,000 registered residents and around 3,000 tourists who arrive on the island each day.