UPDATE 3-Madoff lawyer seeks 12-year term for swindler

* Madoff lawyer asks judge for term less than life

* Lawyer says Madoff met with the SEC to discuss his scam

* Defrauded customers to speak at June 29 sentencing (Adds details on Madoff meeting with SEC, edits throughout)

By Martha Graybow and Grant McCool

NEW YORK, June 23 (Reuters) - Bernard Madoff's lawyer asked a judge to sentence Wall Street's biggest thief to a punishment of less than life in prison, saying the court should not give in to the "mob vengeance" sought by those he defrauded.

Madoff "will speak to the shame he has felt and to the pain he has caused" at his June 29 sentencing hearing, defense lawyer Ira Lee Sorkin wrote in a letter to U.S. District Judge Denny Chin made public on Tuesday.

Madoff, 71, pleaded guilty in March to running a worldwide Ponzi scheme that bilked investors out of as much as $65 billion over two decades. The maximum sentence on all 11 charges, including securities fraud and money laundering, adds up to 150 years in prison.

A 12-year prison term would be sufficient to address the issue of deterrence and to promote respect for the law, Sorkin wrote. He said a sentence of up to 20 years could also be appropriate without "disproportionately punishing" Madoff.

Madoff, a former nonexecutive chairman of the Nasdaq stock market and a once-respected money manager sought after by investors for his seemingly steady returns, has been jailed since he pleaded guilty.