NEW YORK (CNN)—The relatives of three American hikers detained in Iran say they have no information on their whereabouts.

The families are pushing diplomats to help find out exactly where they are, and arrange their release.

Sarah Shourd, Shane Bauer and Joshua Fattal have been in custody since July 31st, when they entered Iran from Iraq without authorization.

Their families say they crossed the poorly marked border by mistake.

Iran’s state television says they ignored warnings.

Secretary of State Hillary Clinton has issued a statement, urging Iran to let the hikers go.

The United States and Iran have not had diplomatic relations since 1979, when militant students took hundreds of Americans hostage at the U.S. embassy in Tehran.