Ahead of U.S. President Barack Obama's trip to Israel next week, more Israelis have continued to add their names to a petition calling for the release of imprisoned Israeli spy Jonathan Pollard.

On Wednesday, Israeli supermodel Bar Refaeli signed the petition, along with actors Zion Baruch, Eli Yatzpan and Shlomo Vishinsky.

Earlier this week, former Israel Defense Forces soldier Gilad Schalit, who was held captive by Hamas in the Gaza Strip for more than five years before being released in October 2011, signed the petition calling for Pollard's release. As of now, more than 155,000 Israelis have signed the petition.

Pollard, 58, was arrested by U.S. authorities in 1985 and later sentenced to life in prison. He is reportedly in poor health.

A new campaign, "Teens waiting for Pollard," was launched on Wednesday. As part of this campaign, people from Israel and around the world will take pictures of themselves displaying the number 28, representing the number of years Pollard has been imprisoned.