The US Senate on Thursday overwhelmingly approved a sweeping new package of sanctions on Iran, aiming to force Tehran to halt its suspected nuclear weapons program by choking off its gasoline imports.

Lawmakers voted 99-0 in favor of the legislation, which was expected to clear the House of Representatives later in the day and go to President Barack Obama to sign into law, ramping up economic pressure on the Islamic republic.

"We must stop Iran from developing a nuclear weapon -- a weapon that would surely threaten the national security of the United States and of Israel," said Democratic Senate Majority Leader Harry Reid.

The bill, which builds on new UN Security Council and European Union sanctions, aims to dry up Iran's imports of refined petroleum products, curb investment in its energy sector, and restrict its access to global banking.

"Our goal is to target Iran where it will hurt the regime the most," Reid said.

World powers led by Washington have accused the Islamic republic of seeking to build nuclear weapons and demanding it freeze its uranium enrichment activity, which can be a key step towards developing an atomic arsenal.

The bill would deny access to US markets to firms that provide Iran with refined petroleum products, like gasoline or jet fuel, that the oil-rich nation must import to meet demand because of a weak domestic refining capability.

The measure also takes aim at firms that do business in Iran's energy sector, including non-US companies that provide financing, insurance, or shipping services.

It could also see non-US banks doing business with certain blacklisted Iranian entities -- including Iran's elite Islamic Revolutionary Guard Corps and several banks -- shut out of the US financial system.

"We will be posing a choice to companies around the world: Do you want to do business with Iran? Or do you want to business with the United States? We don't think that is much of a choice, but we will force companies to make it. They can't have it both ways," said Republican Senator John McCain.

The bill would also enable US states and local governments to divest from foreign firms engaged in Iran's energy sector, and would tighten the existing US trade embargo on Iranian goods by curbing the number of exempted products.

US officials cautioned this week that Iran has anticipated efforts to squeeze its gasoline imports, changing its consumption patterns and stockpiling needed fuel to reduce its dependence.

"This is a vulnerability and we think it's one that could be exploited," Undersecretary of the Treasury for Terrorism and Financial Intelligence Stuart Levey told the Senate Foreign Relations Committee. "It's not a silver bullet."

Undersecretary of State for Political Affairs William Burns told the panel that Iran had decreased its dependence on imports to 25 percent of domestic consumption, instead of 40 percent a few years ago.

The measure also calls for the US government to identify Iranian officials who are human rights abusers and target them for sanctions like a travel ban and asset freeze.

It would also for the first time require companies seeking US government contracts to certify that they and their subsidiaries do not do business with Iran.

"Passage of Iranian sanctions is an important first step, but only a first step," said Republican Senate Minority Leader Mitch McConnell, who stressed that Washington and its allies "must make clear to Iran that the development of a nuclear weapon is unacceptable."