JERUSALEM An Israeli group campaigning for the release of hostages held in Gaza called on Monday for an investigation into the alleged leak of confidential documents by an ex-aide to the prime minister, which may have undermined efforts to secure the captives' release. An Israeli court announced on Nov. 3 that Eliezer Feldstein, a former aide to Benjamin Netanyahu, had been detained along with three others for allegedly leaking documents to foreign media. The leaked documents are said to have