NEW YORK, Jan 24 (Reuters) - The Palestinian militant group Hamas has recruited between 10,000 and 15,000 members since the start of its war with Israel, according to two congressional sources briefed on U.S. intelligence, suggesting the Iran-backed fighters could remain a persistent threat to Israel.

The intelligence indicates a similar number of Hamas fighters have been killed during that period, the sources said. The latest official U.S. estimates have not been previously reported.'