SAN DIEGO (Reuters) - A former United States Navy contracting official on Tuesday became the ninth person charged in a wide-ranging corruption investigation of a Singapore-based defence contractor, officials said.

Paul Simpkins, 60, was arraigned in a federal court in Virginia on one count of conspiracy to commit bribery following his arrest earlier in the day in Haymarket, Virginia, the US Attorney's Office in San Diego said in a statement.

The arrest is the latest in the widening contracting scandal surrounding Glenn Defense Marine Asia (GDMA), the company at the centre of the scandal. "The GDMA investigation is far from over," Naval Criminal Investigative Services (NCIS) Director Andrew Traver said in a statement. "NCIS will follow the evidence where ever it leads to bring to justice those who were involved in perpetrating this massive fraud on the Department of the Navy and the American taxpayer."

Glenn Defense worked in ports throughout the Pacific restocking, repairing, refueling and cleaning Navy ships. Federal authorities say that the company had more than US$200 million (S$266 million) in Navy contracts for more than 10 years.

The company overbilled the Navy for services and then demanded kickbacks from its subcontractors, according to court documents.

According to the affidavit filed with the Simpkins indictment, Simpkins received cash, luxury travel and entertainment, and the services of prostitutes between May 2006 and 2012 in exchange for providing Glenn Defense's president and chief executive officer, Leonard Glenn Francis, with classified information and advocating for contracts to the company.

Simpkins received hundreds of thousands of dollars in cash from Francis, which the affidavit alleges he funneled through bank accounts in the names of his wife and mistress. In exchange, he helped GDMA win contracts in Thailand and the Philippines, the affidavit states.

Simpkins also suspended the bidding powers of a GDMA competitor, and blocked a Navy colleague's investigation of possible overcharging by the company, the affidavit alleges.

Francis pleaded guilty to conspiracy to commit bribery, conspiracy to defraud the United States, and bribery charges on Jan. 15.

Two other company executives, as well as a former Naval Criminal Investigative Services agent, a former Navy commander, the former deputy director of operations for the 7th fleet, and a Navy logistics officer have pleaded guilty to federal charges.

Another Navy commander pleaded innocent to conspiracy and bribery charges.

If convicted, Simpkins faces a maximum sentence of five years in prison and a fine of up to US$250,000.