Karen Michelmore, Dili – East Timor's Court of Appeal has been asked to decide if a controversial new law which grants widespread amnesties for most crimes committed in the past year violates the tiny country's constitution.

President Jose Ramos Horta today said he would send the bill to the court for an opinion on its constitutionality and whether it violates the country's international obligations, before deciding whether he will sign it or veto it.

East Timor's parliament last month quietly passed the law, which could lead to amnesties for thousands of offenders for a wide range of crimes – from fireams offences, crimes against security to larceny.

"Today I'm actually sending it to the Court of Appeal for an opinion on the constitutional implications, whether such a law is in conformity... or violates some of the principles of international law, and in particular our constitution," Ramos Horta told AAP.

"I wouldn't sign... a law with such implications without seeking a clarification from the highest court in this country. I don't have a view one way or another at the moment, once I study the issue from every angle, one dimension is the constitutionality of the law, another is obviously political implications." The court has one month to deliver its opinion.

Both the United Nations and East Timor's government watchdog, the Provedor, have raised serious concerns with the law, including that it will hinder efforts to hold people accountable for last year's political crisis in which 37 people were killed.

East Timor's government has said the law will help the country move forward from last year's crisis of violence, with prosecutors grappling with thousands of cases in the fledgling country's justice system and prisons "bursting at the seams".

But analysts fear the law could spark new tensions in the nation, particularly if jailed former government minister Rogerio Lobato is among those to be released.

In a recent report, think-tank the International Crisis Group said the new clemency law was "apparently intended especially for Rogerio Lobato", who in March was convicted of murder and distributing weapons to civilians during last year's crisis.

"According to Mudansa (Fretilin Reform group) members, Lobato agreed to take the blame for the distribution of weapons in 2006 on condition that he would be amnestied," the report says.

"If he is not, he might try to implicate (former Fretilin Prime Minister Mari) Alkatiri. If he is amnestied, it may have implications for attempts to prosecute others accused of involvement in the 2006 violence."

Deputy Provedor for Human Rights Silverio Pinto Baptista said the victims of last year's violence needed justice.

"Just imagine if the perpetrators of a crime, if they just let them free, and the victims can do their own payback," he said. "They will seek their own justice, not through the law. There's the potential that problems will happen."