By Paul-Marin Ngoupana

BANGUI (Reuters) - Central African Republic rebels have seized two eastern towns and may resume an insurgency against the central government if it fails to free hundreds of political prisoners as agreed in a peace deal, a rebel spokesman said on Tuesday.

Seleka insurgents in the landlocked nation came close to capturing the capital Bangui and overthrowing President Francois Bozize late last year before striking an accord in January under which some of their leaders joined the government.

The pact, signed in Gabon's capital Libreville, saw Seleka fighters lay down their guns in exchange for a government promise to free prisoners and order the withdrawal of foreign African troops reinforcing the national army.

"President Bozize has no intention of applying the Libreville peace agreement," said Seleka spokesman Eric Massi. "If things stay like this, we will show him the consequences. We don't necessarily need to restart hostilities, but it is an option that we have not taken off the table."

He said that Seleka fighters on Monday had stormed into the eastern towns of Bangassou and Gambo, around 900 km (550 miles) from the battered riverside capital Bangui, on Monday and government troops had fled.

"The operation yesterday was aimed at securing our rear bases, because since the Libreville peace accord, President Bozize has been reinforcing his positions instead of embracing peace," he said by telephone.

ANOTHER CRISIS LOOMING?

The country remains one of the least developed in the world despite rich deposits of gold, diamonds and uranium.

The Central African Republic (CAR) government issued a statement over the radio late on Monday condemning Seleka's seizure of the two towns, saying it risked throwing the country back into crisis.

"This attack has undermined all the efforts at applying the Libreville peace deal," said the statement.

A Seleka rebel communiqué on Tuesday accused Bozize allies in the unity government of handing out machetes and clubs to youths in the capital and encouraging them to attack suspected Seleka supporters.

It also accused security forces of illegal arrests and summary executions of political dissidents and urged the government to immediately order the withdrawal of foreign African forces.

Seleka, a coalition of five separate rebel groups, launched its insurgency in early December, accusing Bozize of reneging on a previous 2007 peace deal supposed to provide jobs and money to insurgents who laid down their weapons.

African countries - including Chad, Gabon, Cameroon and the Republic of Congo - deployed hundreds of troops to shore up Bozize's army after a string of defeats forced the army back to within 75 km (45 miles) of Bangui.

The rebels had previously insisted that Bozize's resignation was a precondition for peace and that the president, who seized power in a Chadian-backed 2003 coup, should stand trial at the International Criminal Court.

Aid groups had warned that a rebel attack on Bangui could trigger a humanitarian crisis.

CAR is one of a number of countries in the region where U.S. special forces are helping local soldiers hunt down the Lord's Resistance Army, an unrelated rebel group that has killed thousands of civilians across four nations.

(Additional reporting by Ange Aboa; Writing by Richard Valdmanis; Editing by David Lewis and Mark Heinrich)