NEW YORK (Reuters) - Former American International Group CEO Maurice "Hank" Greenberg has said the insurer is in "crisis" and urged a delay in its annual general meeting scheduled for Wednesday, according to a letter he sent to the board of directors.

"Several top shareholders of AIG have called me expressing deep concern about the persistent and seemingly endless destruction of value at AIG," Greenberg said in the May 11 letter, a copy of which was filed with the U.S. Securities and Exchange Commission on Monday.

The letter followed AIG's announcement last Thursday of a $7.8 billion first-quarter loss, its largest-ever, as a result of a large write-down to the value of securities linked to subprime mortgages. The company, at the time, said it would raise $12.5 billion to strengthen its balance sheet.

"AIG is in crisis," Greenberg said.

AIG spokesman Chris Winans said the company received Greenberg's letter on Monday, and had forwarded it to members of the board.

"The board will respond to Mr. Greenberg's request shortly," he added.

Greenberg's letter follows a lawsuit filed last week by Starr International, a company that Greenberg controls, against AIG and its chief executive, Martin Sullivan, as well as Steven Bensinger, who on Thursday announced he would step aside as chief financial officer to assume another post at AIG.

The suit, filed in New York State Supreme Court in Manhattan, alleges fraud, claiming the insurer misrepresented its exposure to credit default swaps, and seeks to recover at least $300 million in damages.

Greenberg, who parted ways with AIG in 2005 amid an accounting scandal, is chairman of C.V. Starr and Starr International, entities that were once affiliated with AIG, and continue to be the insurer's largest shareholders.

Along with a personal stake, Greenberg controls roughly 12 percent of AIG stock, according to Reuters data.

"The company's shareholders need to absorb the significance of the company's first-quarter losses," wrote Greenberg in the letter this week to AIG's board.

"They (investors) also need time to consider the board's response to the crisis and the issues raised by this letter.

"For this reason and others, a postponement of this week's annual meeting should be considered, so that all shareholders can give careful thought to how best to move AIG forward," Greenberg added.

AIG shares closed down $1.91, or 4.74 percent to $38.87 on the New York Stock Exchange, the lowest level since October 1998.