The Rev. Al Sharpton is going hungry, and he won't eat until he is released from prison, according to Tuesday's New York Times.

The civil rights activist began a hunger strike in jail Tuesday to publicize the Navy bombing exercises on the Puerto Rican island of Vieques and his arrest protesting them, his lawyer said. 

"Both his legal team and his family are concerned about Rev. Sharpton's health, but the hunger strike will continue until the release of the Vieques Four — as long as that takes," Sharpton's attorney, Sanford Rubenstein, said Tuesday. 

Sharpton and three other men — New York City Councilman Adolfo Carrion, state Assemblyman Jose Rivera and Bronx County Democratic Party chairman Roberto Ramirez — were arrested in Puerto Rico for taking part in protests May 1 against the Navy's use of Vieques for military exercises. The men have been dubbed the "Vieques Four." 

The Rev. T.L. Walker, who accompanied Martin Luther King Jr. to jail in the 1960s, met with Sharpton on Monday afternoon, Rubenstein said. 

Walker compared Sharpton's sentence with King's 40 years ago "when he protested Rich's Department Store with a sit-in," Rubenstein said. "The same thing has happened to Sharpton. He's been given twice the jail time just because he had a prior conviction for protesting over the Brooklyn Bridge." 

Opposition to the bombing exercises grew after a civilian guard was killed on Vieques in 1999 by two off-target bombs. The Navy says the training is essential for national security. 

Rubenstein also said that Sharpton and the other three men were denied their constitutional rights because they were not given the right or time to prepare a defense. 

Sharpton was sentenced to serve 90 days by a federal judge in Puerto Rico because of a prior conviction for civil disobedience. The three other men were each sentenced to 40 days. They are being held at the Metropolitan Detention Center in New York. 

The four men could be released as early as Tuesday, once an appeals court in Boston rules on whether they can be released on bail while they appeal their convictions.