American Ronald Adams, the chief executive and owner of the Czech-based truck-maker Tatra has denied graft allegations linked to a Czech defence contract for which he has been charged, Tatra said Tuesday.

The case involves a 2008-2009 military contract for 588 Tatra trucks valued at 2.7 billion koruna (109 million euros, $135 million).

Adams was charged Monday after former Czech defence minister Martin Bartak, accused in 2010 of attempted corruption linked to the same contract, testified against him, a Tatra company spokesman told AFP.

"Within the framework of an investigation into the case in which Mr Bartak is charged with corruption, Bartak said that Mr Adams offered him a bribe," Vladimir Bystrov told AFP.

"Tatra is confident that the ongoing investigation launched on the basis of the testimony of persons already charged with corruption is without foundation," Bystrov said.

While it charged him in the case, a court in the eastern Czech city of Brno on Tuesday decided to release him from police custody.

"The court believes my client is an honest citizen and businessman who has committed no crime," Adams laywer Jiri Matisjasevic told the Czech CTK news agency.

"It is evident that the principle objective is to put in doubt the credibility of Mr Adams as a witness and to intimidate him along with all other persons who dare testify openly about corruption at the highest levels in the Czech state," a Tatra statement said Tuesday.

Bartak, 45, served as deputy Czech defence minister in 2006-8 and defence minister in the ex-communist NATO state from 2009-10.

In 2010 he was accused of attempted corruption based on the testimony of former US ambassador, William J. Cabaniss who served in Prague between 2003-5.

In Transparency International's 2011 Corruption Perception Index, the Czech Republic ranked 57th alongside Namibia and Saudi Arabia on the list of 183 countries, topped by squeaky clean New Zealand and ending with Somalia.