VIENTIANE, Laos, AP

The communist government of Laos warned people Thursday not to travel at night without official identification amid signs that an unofficial curfew had been imposed.

The tightened security follows a series of mysterious bomb blasts in the capital, Vientiane, that have injured dozens.

Foreigners stopped at police checkpoints on main roads in the city around midnight have been questioned and sometimes fined 50,000-120,000 kip (US$6.25-15), apparently for violating the unofficial curfew, foreign residents and diplomats said.

A Foreign Ministry official said “people are entitled to travel after midnight for purposes of work or private business.”

“But they must carry identification,” said the official, speaking on condition of anonymity. He did not say what would happen to those without identification.

But residents said they risk a 30,000 kip (US$3.75) fine and arrest if they have no ID card. The residents spoke on condition of anonymity. He said the new security measures have been announced on public radio.

Since late March, a series of bomb blasts shattered the calm of the normally sleepy Lao capital, injuring dozens of people at targets including the central bus station, post office, main market and a tourist restaurant. Provincial towns have also been targeted.

Nobody has claimed responsibility for the attacks, which some analysts believe are the result of rifts within the military. The government has not identified any suspects.

An announcement posted by the Australian Embassy in Vientiane this week said the travel restrictions appeared to have been introduced as the National Assembly sat for a plenary session last week, but had not been officially confirmed.

But there were official warnings to bar and club owners about staying open late. Armed soldiers are now prominent on the streets at night and village militia are active in the suburbs, residents said.

“We have to close early each night, even if we cannot finish our work,” said one foreign businessman in the construction trade, whose staff sometimes work late night office shifts. He did not want to be named.