Convicted Israeli spy Jonathan Pollard was taken Monday to the hospital for an urgent operation, suggesting a further deterioration in his health.

Pollard has been suffering lately from many medical complications in his gallbladder and kidneys. He was supposed to undergo surgery last week, but it was postponed due to a visit by Israel's Ambassador to the U.S. Michael Oren.

Pollard's wife, Esther, said that since receiving the news from the prison management she is "climbing on the walls." "I am so worried I don't know what to do with myself," she said. "The last time a similar thing happened the doctor told Jonathan that he was saved from death at the last minute."

MK Uri Ariel (National Union), who chairs the lobby for Pollard in the Knesset, said Tuesday that "Pollard's imprisonment is a humanitarian disgrace," adding  "I call again on President Obama to release him immediately, not because he is not guilty, but because you can't keep a sick and non-dangerous man imprisoned for so many years."

Pollard was arrested in 1986 as he tried to seek asylum at the Israeli Embassy in Washington. He was convicted of espionage for Israel and was sentenced to life imprisonment.

Since then, the U.S. has steadfastly refused to shorten Pollard's sentence or grant him a pardon, despite requests by Israeli prime ministers, ministers, and MKs.