WASHINGTON, (Reuters) – Congress yesterday  approved tough new unilateral sanctions aimed at squeezing  Iran’s energy and banking sectors, which could also hurt  companies from other countries doing business with Tehran.

The House of Representatives passed the bill 408-8 and sent  it to President Barack Obama for signing into law. The Senate  had approved it 99-0 earlier in the day.

Congress wants to pressure Tehran into curbing its nuclear  program, which Washington suspe

U.S. lawmakers from both parties have been pushing for  months to tighten U.S. sanctions on Iran. At the Obama  administration’s request, they held off until the U.N. Security  Council and the European Union agreed on new multilateral  sanctions. But the lawmakers then declared that still tougher  measures were needed.

“The U.N. sanctions, though a good first step, are quite  tepid. And they are tepid because there are other members of  the Security Council who want to keep doing that business with  Iran. … The United States … has to pass these unilateral  sanctions,” Democratic Senator Barbara Mikulski said.

The bill penalizes companies supplying Iran with gasoline  as well as international banking institutions involved with  Iran’s Islamic Revolutionary Guard Corps, its nuclear program  or what Washington calls its support for terrorist activity.

It would effectively deprive foreign banks of access to the  U.S. financial system if they do business with key Iranian  banks or the Revolutionary Guards.     Such banks would be “shut out of the U.S. financial  system,” said the bill’s House author, Foreign Affairs  Committee Chairman Howard Berman. He is a Democrat.

Global suppliers of gasoline to Iran could also face bans  on access to the U.S. banking system, property transactions and  foreign exchange in the United States. Iran depends on gasoline  imports because it has insufficient refining capacity.    “Because of this legislation, we will be posing a choice to  companies around the world. Do you want to do business with  Iran, or do you want to do business with the United States?”  Republican Senator John McCain said during Senate debate.

U.S. companies are already prohibited from doing business  with Iran. Foreign companies with big investments in Iran’s  energy sector also can be sanctioned under current U.S. law.  But many U.S. lawmakers say this has not been enforced.      Some companies worldwide, such as Italy’s oil and gas  company Eni and French energy giant Total have been backing  away from business with Tehran amid the U.S. drive to isolate  Iran.