The anti-corruption watchdog Transparency International listed Thailand on Tuesday as a country with inadequate safeguards against graft in defence and weapons deals.

Thailand "is at high risk of corruption in the defence sector," said the group - along with China, Russia, Singapore and India.

Transparency International is based in Germany, but the defence report was released on Tuesday in London by Transparency International UK's Defence and Security Programme. It is available on the web at www.defenceindex.org.

Other countries were judged worse than Thailand's high risk group by the anti-corruption agency. The Philippines, Sri Lanka, Iran and Afghanistan are among those rated at "very high risk" of corruption in arms sales and purchase.

The United States, Britain, Sweden and South Korea were among countries judged to be at low risk.

The survey looked not only at the potential for corruption in defence contracts, but also at the risk of abuse of defence budgets and the risk of corruption in the armed forces.

Thailand, it said, was not among the 10 countries with "highly effective" parliamentary scrutiny of defence policy, nor does Thailand have any laws or regulations protecting whistleblowers who expose graft in weapons purchase.

Transparency International said its defence survey covered 82 countries, which accounted for 94 per cent of global military expenditure in 2011, worth $1.6 trillion. The group estimated corruption was at least $20 billion.

The survey said corruption in weapons deals is dangerous because troops "may well have equipment that doesn't work", not to mention the drain on the national treasury.