A civil liberties group has sued the US government, saying various agencies have failed to provide adequate documents related to what it calls the sweeping monitoring of Americans' international communications. The American Civil Liberties Union said in the lawsuit, filed on Monday in the federal court in Manhattan, that its Freedom of Information Act requests since May had been largely ignored by the National Security Agency, the Central Intelligence Agency, the Department of Defence, the Department of Justice and the Department of State. It sought a court order to force the government to turn over information about the rules governing how it monitors the international calls and the e-mails of Americans. The group said it wanted to learn what protections were given to Americans whose communications were monitored and whether they were legally sufficient. The lawsuit said legal standards and limitations were sought, rather than operational details. In a blog, the union's staff attorney Alex Abdo said revelations over the last year had increased the public's understanding about how the government conducts surveillance when it sweeps up Americans' international communications when it takes place on US soil. But he said there was little known about an executive order which allows US agencies to monitor Americans' communications in other countries. According to the lawsuit, the executive order was signed in December 1981 and modified numerous times since.