Police are checking the call records and contact details stored in the mobile phones of the five foreign crewmembers of the cargo plane held at Don Mueang Airport since last weekend.
The aircraft was impounded after being found to contain a large cache of smuggled weapons.
A Special Branch team of police yesterday obtained the handsets at the Bangkok Remand Prison where the five are being detained, but did not interview them, a prison source said.
The source said Viktor Bout, an arms dealer who is being detained at the same prison awaiting a court order over an extradition request from the US authorities, had not been visited or questioned by any Thai or foreign security authorities, despite media speculation that he may have been involved with the smuggling operation.
Meanwhile, Defence Minister Prawit Wongsuwan said it was for the government to decide whether to store or destroy the seized weapons, but the military could safeguard them if the former option were taken.
Deputy Prime Minister Suthep Thaugsuban said he "had no problems" with Foreign Minister Kasit Piromya's statement that all weapons needed to be destroyed. Kasit had made the remark in response to a statement by Prime Minister Abhisit Vejjajiva that they could be utilised by the Thai military.
Asked about the cost of the weapons' destruction, Suthep said only that Thailand would need to follow precedents and it would soon be known what options the country had in relation to the relevant UN protocols.