A day earlier, the quartet and their firm had been indicted by a federal grand jury in Philadelphia on one count of conspiracy to bribe Vietnamese public officials in violation of the Foreign Corrupt Practices Act (FCPA) and four substantive counts of breaching the FCPA, the department said.

According to the indictment, the four worked for Nexus Technologies Inc., a Delaware company with offices in Philadelphia, New Jersey, and Vietnam.

The indictment said the firm had purchased a wide variety of equipment and technology in the maritime, aviation and communications sectors for export to Vietnam.

The indictment alleges that from 1999 through 2008, the four defendants had conspired to pay bribes worth $150,000 to several Vietnamese individuals to win contracts for Nexus Technologies Inc.

The clients of the defendants are allegedly several companies under several Vietnamese ministries and government agencies, the indictment said.

The indictment alleges that Nam Quoc Nguyen had negotiated contracts and bribes while Lukas negotiated with vendors in the US

The case was probed by the Federal Bureau of Investigation and the U.S Department of Commerce.

The Philadelphia Business Journal reported the defendants have yet to comment on the case.

The conspiracy count against the individual defendants carries a maximum penalty of five years in prison, a fine of the greater of $250,000 or twice the gain; and a three year term of supervised release. The FCPA counts charged against the individual defendants each carry a maximum penalty of five years in prison, a fine of the greater of $100,000 or twice the gain; and a three year term of supervised release. Nexus Technologies Inc., faces a maximum $2 million fine per count, if convicted.

Vietnamese authorities have yet to comment on the case.

Reported by Thanh Nien staff