WASHINGTON (AP) — Republican and Democratic lawmakers are proposing to step up sanctions against North Korea by punishing companies, banks and governments that do prohibited business with it.

The bill crafted by leaders of the House Foreign Affairs Committee and introduced Friday is modeled on sanctions in force against Iran.

Congressional staffers say it’s intended to improve enforcement of existing sanctions, but also expand them.

The measure reflects growing concern over North Korea’s nuclear weapon and missile development, and frustration over the failure of US policy to stop it.

The bill was introduced by Republican Rep. Ed Royce and Democratic Rep. Eliot Engel. Its prospects for becoming law are uncertain.

The draft bill does not name any particular entities, but potentially could impact companies and banks in China through which the North conducts most of its business.

The draft gives the president authority to sanction governments for illicit dealings with North Korea, but also authority to waive the bill’s provisions on a case-by-case basis on national security grounds.

The legislation could irk Beijing at a time when the Obama administration seeks greater Chinese cooperation in pressuring Pyongyang to end war threats and honor past commitments on denuclearization.

Beijing signed up for the toughest UN sanctions yet on North Korea in response to a February nuclear test.

But Royce has called for tougher unilateral steps, as the U.S. government did in 2005 against a Macau-based bank because it held about $25 million in North Korean funds. That measure had a significant impact, but proved complicated to undo when nuclear negotiations with North Korea finally got back on track.

Copyright 2013 The Associated Press.