Lagos, Nigeria (CNN) -- Nigerian investigators say they have filed charges against former U.S. Vice President Dick Cheney and others connected to the energy services company Halliburton, accusing them of paying bribes to secure a lucrative natural gas project in the 1990s.

Cheney and nine others are accused of charges that include "conspiracy and distribution of gratification to public officials," Femi Babafemi, a spokesman for the country's Economic and Financial Crimes Commission, said Wednesday.

The investigation is part of a long-running case involving Halliburton and a subsidiary firm, Kellogg, Brown and Root, over alleged bribes paid to Nigerian officials to secure $6 billion worth of contracts for a liquefied natural gas project in the Niger Delta.

Many observers in Nigeria regard the move as a publicity stunt by the commission ahead of national elections this April and a symbolic effort to display resolve against government corruption.

The agency has had limited success in getting successful prosecutions and hasn't charged any high-profile people since its top commissioner was removed from the body in 2007.

After the country's high court sets a trial date, authorities could pursue extradition.

The bribes allegedly amounted to $180 million between 1994 and 2004.

Kellogg, Brown and Root was one of four large international construction firms that built the natural gas plant.

The firm pleaded guilty to foreign bribery charges in the United States last year and paid a $402 million criminal fine, the U.S. Justice Department said. KBR and Halliburton also paid another $177 million to settle civil complaints related to the bribery, the Justice Department said.

Investigations in Nigeria, however, have been ongoing, and there are allegations the bribes went all the way to the top, to aides, officials, and possibly then-President Olusegun Obasanjo.

Cheney's lawyer has said in the past that there is no reason to suspect his client is guilty.

"This matter involves the activities of an international four-company joint venture (which included KBR, then a subsidiary of Halliburton) well over a decade ago," said attorney Terrence O'Connell.

"The Department of Justice and the Securities and Exchange Commission investigated that joint venture extensively and found no suggestion of any impropriety by Dick Cheney in his role of CEO of Halliburton."