WASHINGTON -- President Shimon Peres will appeal to US President Barack Obama on behalf of convicted Israeli spy Jonathan Pollard on "humanitarian" grounds, he said soon after his arrival in Washington Monday.

Peres said he will raise the issue of commuting Pollard´s sentence in a private meeting with Obama that will part of the multiple days of events scheduled to celebrate his being honored with the Presidential Medal of Freedom.

Peres was scheduled to begin his visit with a ceremony receiving him at the Pentagon later on Monday.

Peres has already made an appeal on behalf of Pollard, a former US Navy analyst who has served more than 25 years of his life sentence and is in ill health. A bevy of prominent Israelis have lent their names to a 70,000-signature petition asking that he be released.

Speaking to reporters briefly from Blair House, the official White House guest residence at which he is staying, Peres said that as a president himself who has the ability to grant pardons, he understands the many concerns they raise. He would not speculate on how Obama was likely to respond to the appeal.

Peres also harshly condemned the anti-Semitic graffiti found at Yad Vashem on Monday, calling it "horrifying."

"There are limits to criticism," he said. "All people must stand as one, unequivocally, against this phenomenon."

Peres will participate in a conversation with US Secretary of State Hillary Clinton at the Saban Center of the Brookings Institution on Tuesday before being feted at a White House dinner in his honor on Wednesday night. He returns to Israel on Thursday evening. (© 1995- 2011, The Jerusalem Post 06/12/12)