"The investigation so far has not allowed us to find sufficient evidence so as to file a complaint against these people," Ferrufino told reporters on announcing a group of nine was set free yesterday. A first group of seven was earlier released late Thursday.

"So we decreed the conditional release of these citizens," Ferrufino said adding that an investigation would continue "in case new elements are turned up along the way."

The United States yesterday had warmly welcomed the detention of the 16 at Santa Cruz in southeast Bolivia, who police said had all been carrying false documentation.

The official Bolivian News Agency said a French tip indicated that nine of those detained were planning to hijack a plane bound from La Paz to Buenos Aires, with a stopover in Santa Cruz, to use it to hit US targets.

"We congratulate the Bolivian police. They took quick, decisive action in response to the information provided by the French police," a State Department official told AFP in Washington.

The arrests were part of a joint operation with French intelligence, Interior Minister Alfonso Ferrufino said after "Operation Ramadan" Thursday at Viru Viru International Airport in Santa Cruz.

Ferrufino said French authorities had requested the 16 be detained, on information "that would link these people to terrorism."

Nine of the Bangladeshis were in transit to Buenos Aires, and the other seven were seeking residency in the Andean nation.

Ferrufino said it was clear that in some cases there were irregularities in processing the Bolivian residence visas.

Ferrufino Thursday would not comment on reports the men were planning to hijack an airliner, other than to say "that was the version that came from the French police. We cannot determine if that was going to happen or not."

"We have no information to prove or disprove the theory that these individuals might be terrorists at this point," the State Department official added.