* Coup determination could trigger cut off in most U.S. aid
* U.S. official says not in national interest to makedecision
* Lawmakers suggest they may amend U.S. laws on coup, aid (Adds quotes, details)
By Arshad Mohammed and Patricia Zengerle
WASHINGTON, July 25 (Reuters) - The Obama administrationtold Congress on Thursday it does not plan to make adetermination on whether a military coup occurred in Egypt,avoiding a decision that would force the cut off of most of theannual $1.55 billion in U.S. aid.
U.S. Deputy Secretary of State William Burns delivered themessage in separate briefings to senior members of the U.S.Senate and the House of Representatives, several lawmakers toldreporters after meeting the number two U.S. diplomat.
The question of whether a military coup took place has vexedthe White House, which generally wants to be seen as supportingdemocratically elected leaders but which had no love lost forousted Egyptian President Mohamed Mursi.
Under U.S. law, most aid must stop to "any country whoseduly elected head of government is deposed by military coupd'etat or decree" or toppled in "a coup d'etat or decree inwhich the military plays a decisive role."
However, the law does not actually oblige the White House tomake a decision.
"The law does not require us to make a formal determinationas to whether a coup took place, and it is not in our nationalinterest to make such a determination," said an Obamaadministration official who spoke on condition of anonymity.
Speaking after the session with Burns, Senator Bob Corker,the top Republican on the Senate Foreign Relation Committee,said the Obama administration might never make a decision on thematter and suggested that U.S. law needed to be changed.
"No determination has been made. It's possible that nodetermination will ever be made," Corker told reporters.
The Egyptian armed forces deposed Mursi on July 3 after hugestreet protests against his rule, clearing the way for lastweek's installment of an interim Cabinet charged with restoringcivilian government and reviving the economy.
Current and former officials have said the administrationhas no appetite for terminating aid, which runs at about $1.55billion a year, $1.3 billion of which goes to the military, forfear of antagonizing one of Egypt's most important institutions.
Nor does it wish to increase instability in the mostpopulous Arab nation, which is of strategic importance becauseof its peace treaty with close U.S. ally Israel and its controlof the Suez Canal, a vital waterway for the U.S. military.
"Egypt is a very strategic country in the Middle East andwhat we need to be is an instrument of calmness," Corker toldreporters, suggesting that the U.S. laws be changed so as toallow greater flexibility.
"We need to deal with our laws in such a way that allow usto continue to be that instrument of stability in the region,"he added. "It's likely that very soon we will try to deal withthis issue, which is a quandary, legislatively." (Additional reporting by Roberta Rampton; Editing by EricBeech)