The French intelligence officer who led the 1985 bombing of the Rainbow Warrior, the Greenpeace ship protesting against nuclear tests in the Pacific, now lives in America where he heads an arms firm selling weapons to the FBI, Pentagon, and the department of homeland security, the Guardian has learned.

The presence in America of Louis-Pierre Dillais and the sensitive nature of his dealings with the US government has led to calls from Greenpeace for his deportation .

The attack engineered by the French intelligence services on an unarmed ship docked in a friendly harbour - the Rainbow Warrior sank off Auckland, New Zealand - brought widespread criticism of the French government. A Portuguese photographer on the ship drowned after being trapped below deck.

Two of the French agents involved in the bombing operation later served jail sentences for manslaughter.

However, Mr Dillais, an operative of the French external intelligence service DGSE who was identified by French media reports as the man who commanded the attack - codenamed Operation Satanique - was never brought to trial.

A lieutenant colonel in the French military and former director of the French military's underwater combat training base on Corsica, Mr Dillais reportedly led the team of divers who placed limpet mines on the ship's hull. He is now employed as an executive in the US subsidiary of a Belgian arms manufacturer, FN Herstal.

FNH USA has its headquarters in a modest office, strewn with boxes, in McLean, Virginia, just down the road from the CIA. The suite is located above the Association for Organ Procurement Organisations on the second floor of a brown brick building nestled among doctors' offices, nail salons and other businesses. McLean is one of Washington's wealthiest suburbs.

According to the company website and industry publications, FN Herstal and its US subsidiary supply combat assault rifles to the Pentagon, handguns to the secret service, and sniper rifles to the FBI. The company also produces an underwater machine gun, and provides equipment to police departments across the US.

The subsidiary alone turned over nearly $2.5m (£1.25m) of business in federal contracts in 2005, according to FedSpending.org. The site notes that only $93,000 worth of those contracts were fully competitive.

Last year, FNH reached a settlement with the family of Victoria Snelgrove, a university student from Boston who was killed when she was hit with a pepper spray pellet fired by a police officer.

Greenpeace, which tracked Mr Dillais to Virginia, has launched a campaign demanding that the American authorities explain why he was let into the United States.

The organisation wrote to the department of homeland security in September last year demanding Mr Dillais's deportation.

US immigration regulations ordinarily bar people who have been convicted of a violent crime, or linked to acts of terrorism.

"We think the government should be setting a much higher standard on the people it does business with," said Mark Floegel, a senior investigator at Greenpeace.

"It is amazingly two-faced to be buying arms from someone who is an admitted terrorist. He has not denied his role in Operation Satanic."

Mr Dillais is believed to have lived in the US for a number of years in an elegant neo-Georgian townhouse only steps away from the main FNH USA office. The home, decorated with cream carpets and paintings of sailing ships and French villages, was put up for sale last week.

He refused to speak to the Guardian. An assistant to Mr Dillais at FNH USA said: "I have to say frankly he is not available for an interview, and he won't be any time."

However, Mr Dillais has acknowledged his role in the sinking of the Rainbow Warrior, telling a television crew from the New Zealand state broadcaster, TVNZ in 2005: "I'm sorry for the loss of life," he told the station. "It was an unfortunate accident. I'm sorry for the family, but what can you do?"

Officials from the state department, the department of homeland security, the FBI and the French embassy would not comment directly on Mr Dillais's presence in the US, or whether he was at risk of deportation. However, US officials did say that anyone involved in an act of terrorism would not be welcome in America.

"The law is very clear: persons involved in acts of terrorism are not admitted into the United States," said Kelly Klundt, a spokeswoman for the customs and border protection agency.

Bill Carter, a spokesman for the FBI, said: "If an individual has been involved in terror-related activity and is in the United States than obviously that individual would be of interest to the FBI."

But the Bush administration's record in enforcing its own regulations is inconsistent. Washington has consistently resisted demands from Venezuela for the extradition of Luis Posada, a Cuban exile who is accused of blowing up an airliner with 73 people on board. He denies the charge.

About a dozen French operatives were believed to be involved in the bombing of the Rainbow Warrior. However, only two were ever brought to trial, and served three years in French Polynesia after being convicted of manslaughter. In 1991, the New Zealand government withdrew all of the outstanding warrants against the French agents.

Mr Dillais, meanwhile, was promoted to colonel, and by 1993 headed a small intelligence unit reporting directly to the then defence minister, François Leotard. It was in that post, according to press reports at the time, that Mr Dillais became involved in arms dealing, reviewing export contracts of French firms.

But by 1996, Mr Dillais was embroiled in another scandal when he was bugged during an investigation into charges that money from Saudi arms sales was illegally diverted to the failed presidential campaign of Edouard Balladur.

There is no indication that any legal action was taken against Mr Dillais. However, press reports soon afterwards noted that he had been passed over for a posting to the French embassy in Washington.

Mr Dillais did not resurface in the public realm until a January 2005 press release put out by FNH USA announcing a contract to supply US special forces with assault rifles. The press release identified Mr Dillais as president and chief executive of FNH USA.

Backstory

On the night of July 11 1985 French divers rowed out to a ship anchored off Auckland and placed two limpet mines on its hull, sinking the vessel and killing a photographer aboard. That ship was the Rainbow Warrior. It had just evacuated a group of Pacific islanders contaminated by US nuclear testing in 1956 and was about to set sail for the French nuclear test zone at the Mururoa atoll. The act of sabotage on an unarmed ship, at anchor in the port of a friendly country, created an international scandal. France admitted in 2005 that its secret services had ordered the attack. Only two of the plotters were brought to trial. A New Zealand court sentenced them to 10 years for manslaughter but they were transferred to French territory and quickly freed.

· This article was amended on Tuesday May 29 2007. We referred to the New Zealand state broadcaster as NZTV when it is in fact called TVNZ. This has been corrected.