By Michele Paduano BBC News

A pair of oversized cuffs were received by Customs in 2003

The Foreign and Commonwealth Office (FCO) has been accused of delaying an investigation into the alleged export of goods that could be used for torture, taped meetings with Customs officers reveal.

For more than two years, HM Revenue and Customs has been investigating claims Birmingham firm Hiatts illegally traded large handcuffs which can be used as leg shackles.

The company denies any wrongdoing.

The recorded conversations indicate the FCO's failure to provide Customs with information has led to a delay in any decision about whether there are grounds for a prosecution.

Foreign Secretary Jack Straw rejects the suggestion the FCO has held up the Customs probe.

Enforcement powers

In March 2003, Customs officials took as evidence a pair of oversized handcuffs bought from the US over the internet, stamped with the Hiatts mark.

As part of their investigation into the matter, Customs requested information from both the Department for Trade and Industry and the FCO.

The BBC has received taped conversations which capture a senior Customs officer being asked if the FCO could be forced to provide the information requested of it.

I entirely reject any suggestion the FCO has not provided full assistance Jack Straw

The official responded: "There are enforcement powers that can be used."

The UK government has stringent rules about the export of leg cuffs and even large handcuffs need a special licence before they can be exported, in case they are used as leg cuffs.

In 1999, when the Independent newspaper made allegations about the export of oversized handcuffs, then Foreign Office minister Peter Hain supported Hiatts.

He said any oversized Hiatts stock found in the USA was made before 1984, but said the regulations would be tightened.

The oversized cuffs taken as evidence by Customs were bought in 2001.

Internet purchase

Foreign Secretary Jack Straw was made aware of the allegations about delays to the Customs investigation in 2003, when the matter was raised by the Foreign Affairs Select Committee.

Then committee member David Chidgey told Mr Straw he had an invoice for the purchase via the internet of a Hiatt model 5000 heavy-duty nickel leg cuff.

He said it was made in the UK but later purchased in the US.

In a letter to the BBC, in response to the allegation that the FCO has held up the latest Customs investigation, Mr Straw wrote: "I entirely reject any suggestion the FCO has not provided full assistance (to Customs)."

He wrote that the FCO's legal advisers had complied with all the requests Customs made to the department.

"They have responded promptly on each occasion, and in accordance with the usual rules for disclosure of documents."

Hiatts has declined to answer any questions, but says it has not illegally exported any of its products.