A U.S. House committee has approved a bill on toughening sanctions against North Korea, Iran and Syria with all three accused of being involved in proliferation activities, congressional sources said Thursday.

The House Foreign Affairs Committee unanimously passed the Iran, North Korea, and Syria Nonproliferation Reform and Modernization Act by voice vote Wednesday. It was introduced in June by Rep. Ileana Ros-Lehtinen (R-FL) who chairs the committee along with Rep. Brad Sherman (D-CA), according to the sources.

"The continued collaboration between Iran, North Korea and Syria helps drive the dangerous programs and policies of each of these rogue states, and endangers the United States and our allies.

The threats posed by these rogue regimes to free nations, and to the oppressed people of these three countries, grows every day,"

the committee said.

The bill is to amend the existing Iran, North Korea and Syria Nonproliferation Act by expanding the range of proliferation sanctions and the activities subject to sanctions.

It amends reporting requirements to include information on people who have acquired materials mined or otherwise extracted within the territory of the three nations for the purpose of aiding their weapons of mass destruction programs.

It also expands sanctions applicable to certain foreigners and places restrictions on nuclear cooperation with countries aiding proliferation by the states.

"The revision bill is especially meaningful in that the notion of the so-called secondary boycott to sanction not only countries directly dealing with the three nations but also the third nations that deal with them," a diplomatic source said. "The system has been used to sanction Iran."

The bill has yet to be approved by the entire House and the Senate.

The source said the legislation process is expected to be smooth since both the Democratic and Republican parties support it. (Yonhap News)