The senators said initiatives to prevent "catastrophic terrorism" will be discussed at the summit, and the possibility of Bangladesh becoming "a failed state and a base of operations for international terrorist organisations should be part of those discussions."

According to the letter, nine US senators and seven representatives said they are concerned that Bangladesh has become increasingly plagued by political violence and instability.

In recent times, several US lawmakers separately expressed concerns over the human rights situation in Bangladesh. But this time, both Republicans and Democrats jointly moved against the political violence in Bangladesh.

The letter said, "If these alarming trends continue, there could be serious consequences for regional peace and security as well as international terrorist activity in the region."

They said attacks on Awami League President Sheikh Hasina, British High Commissioner Anwar Choudhary, and assassination of former finance minister Shah AMS Kibria "illustrate the depth of the problem of political violence in Bangladesh."

"Indeed, the hundreds of coordinated attacks across Bangladesh that occurred on August 17, 2005 indicate that the violence is on the rise," they wrote.

The congressmen requested the president to place a three-point proposition for a full, fair and independent investigation: Send an investigation team to review the investigation and determine whether it has been conducted effectively; appoint a UN special envoy to examine the Kibria case and investigate and report on the broader issue of political violence; send independent UN monitors to Bangladesh if the Kibria case goes to trial.

"We believe this case has great importance for the cause of justice in Bangladesh and that the steps outlined above are urgently needed," they said.

Quoting State Department's Country Reports on Human Rights, the senators said Bangladesh is plagued by corruption and judicial inefficiency. The lower courts are under the authority of the executive and they lack independence.

They said that the Transparency International (TI) has given Bangladesh one of the worst ratings in the world for corruption, emphasising that "corruption has assumed serious proportions and it has infected every nook and corner of the society."

Among the 145 countries surveyed for the TI rating, Bangladesh is tied with Haiti as the country most widely perceived as corrupt.

The US senators are Edward M Kennedy, John E Sununu, Patrick J Leahy, Lincoln D Chafee, Barack Obama, Olympia J Snowe, Barbara Boxer, John F Kerry and Jack Reed. The US representatives are Barney Frank, John W Olver, John F Tierney, James P McGovern, Gary L Ackerman, Martin T Meehan and Alcee L Hastings.