Dili – Security forces fired tear gas and rubber bullets at gangs of youths in East Timor's capital Sunday, after an explosion went off at a base for Australian troops and houses were set ablaze, officials and witnesses said.

At least six people were injured in the violence, which occurred days after politicians failed to decide who should lead a new coalition government.

East Timor's ruling elite remain bitterly divided a year after factional fighting between police and army units spilled onto the streets, killing 37 people and driving 155,000 others from their homes.

Order was largely restored with the arrival of international troops, but isolated incidents continue and – with inconclusive parliamentary elections last month – the future remains uncertain.

An explosion occurred at the heliport used by Australian troops on Sunday night, said Ivan Benitez, a spokesman for the International Stabilization Force, adding that no one was injured in the blast and that an investigation was being conducted.

At least one house was burned to the ground and others were on fire in the capital, Dili. Gangs of boys also were burning tires in the streets, said UN police spokeswoman Monica Rodrigues, adding that "police dispersed them by firing tear gas and rubber bullets."

At least six youths were admitted to the main hospital but their injuries were not life-threatening, doctors said.

East Timor, a former Portuguese colony of less than a million people, faces major security, humanitarian and economic challenges just five years after it became Asia's newest state in a UN-backed independence vote.

Unemployment hovers at around 50 percent, and aid agencies have warned that a fifth of the population is threatened by food shortages after crop failures.

Rival political forces have until July 30 to decide who should lead a new coalition government, but talks headed by President Jose Ramos-Horta on Thursday yielded no results.

Leaders of the Fretilin party, which won the most votes in last month's elections but not a majority, met with an alliance headed by the new party of independence hero Xanana Gusmao, the National Coalition for the Reconstruction of East Timor.

Both sides rejected calls for power-sharing, however, apparently split over who should take the top job of prime minister.