A senior Thai general has rejected reports that the army planned to rid the kingdom of the influence of controversial former premier Thaksin Shinawatra years before it seized power in May.

"So far as I know, there was no advance planning, because if it were planned that would be illegitimate," Lieutenant General Chatchalerm Chalermsukh told the BBC in an interview published on Thursday.

"If you're wondering why this (the coup) happened so smoothly, that was because forces were already deployed in the city (Bangkok)," he claimed.

His comments came after local media reported that Suthep Thaugsuban, the leader of mass protests that crippled the former administration, said he had been advising the army chief who led the coup on how to tackle Thaksin for four years.

The Thai military seized power on May 22 after several months of protests that saw 28 people killed and hundreds of others wounded, paralyzing the government of former prime minister Yingluck Shinawatra - Thaksin's younger sister.

It was the latest chapter of a seemingly-intractable political crisis that broadly pits Thaksin - a former premier who was toppled by a coup in 2006 - and his supporters against a royalist establishment backed by parts of the military and judiciary.

The government says the army takeover was necessary to restore order to the country, ruling out elections for at least a year to pass political reforms, including crafting a new constitution.

In the BBC interview, army deputy chief of staff Chatchalerm said Thaksin, who lives in self-imposed exile in Dubai to avoid prison for a corruption conviction, and his family could still return to Thai politics.

"Everyone who is Thai and is qualified can take part in that election - even the family of Thaksin Shinawatra," he said.

"We are not hunting Thaksin, as we did before. ... We would like to see him come back and fight the legal charges against him. If he is confident he can win, then he will be able to return to politics."

Thailand's new military rulers have suspended democracy since seizing power, imposing martial law, banning public rallies and censoring the media to stifle any dissent.

The government has summoned and detained several hundred people, the majority linked with the deposed Puea Thai government and the Shinawatra family's "Red Shirt" supporters.

But Chatchalerm said "the military belongs to all Thai people, not just one group".

"None of the summonsed people have been charged with serious offenses. We only charge them with disobeying our orders. When these cases reach court they will be processed in a normal legal way," he said.