Canada, the U.S. and the U.K. are limiting Iran's access to much of the world's financial system in an attempt to isolate the country's regime.

The sanctions Canada announced Monday also add the leadership from the Revolutionary Guard to the list of people designated for sanctions and expands the list of prohibited goods.

"The regime in Iran poses a significant threat to regional and global peace. We will do what it takes to isolate the regime and to minimize the risk that it poses to global peace," said Government House Leader Peter Van Loan.

Although the sanctions expand the list of prohibited goods to include those used in the oil and gas industry, a release from the Department of Foreign Affairs notes the new prohibitions do not apply to contracts entered into prior to Nov. 22, 2011.

The new prohibition covers all financial transactions not already banned, except for the already-signed contracts and personal remittances under $40,000, which is intended to let Canadians send money to family members.

The prohibition is total and includes transactions for payment on export or import of goods and services, a Canadian official said. The goods prohibition applies to Canadians outside Canada too.

The moves follow a recent report by the International Atomic Energy Agency that suggested Iran was working on a weapons program under the cover of a civilian energy project.

Britain announced its own sanctions earlier Monday, with U.S. Secretary of State Hillary Clinton adding American sanctions later in the day.

It's all in an effort to pressure Tehran to halt its suspected nuclear weapons program, which Iran says is for peaceful purposes.

Clinton said this is the first time the U.S. is targeting Iran's petrochemical sector, making it illegal to provide equipment and technology for the oil and gas industry.

"The impact will only grow unless Iran's leaders decide to change course," Clinton said.

"Today's actions do not exhaust our opportunities to sanction Iran."

"So far, we have seen little indication that Iran is serious about negotiation on its nuclear program. And until we do, and Iran's leaders honour their obligations, they will face increasing sanctions."

Treasury Secretary Timothy Geithner says this is the first time America is identifying the entire Iranian banking sector as a threat.

"We have dramatically reduced their access to the international financial system. Iranian banks are losing their ability to do business around the world," he said.

Report suggested weapons program

The moves come after a UN nuclear agency's recent report suggesting Iranian work on an atomic weapons program.

NDP Foreign Affairs critic Hélène Laverdière, a former diplomat, says sanctions do work. Laverdière wants the government to keep working diplomatically, especially pressing China and Russia, allies of Iran.

"Iranian banks are suspected of financing the nuclear development program, so if you cut the financing mechanism, if you don’t help these people who finance the program, well, you’re doing real concrete action," she said.

"Putting in sanctions is one thing, but there’s a lot of hard work to be done here in Canada and abroad with our partners."

On Saturday, Defence Minister Peter MacKay said Canada — which is fresh from participating in the NATO intervention in Libya — isn't about to rush into similar military action elsewhere.

"We're not there yet," MacKay said of Iran. "I think there are a number ... of other things we can do first."

Canada last imposed sanctions on five Iranians after a foiled plot to assassinate Saudi Arabia's ambassador to the U.S. in October. American officials said Iran's regime was behind the plot.

Britain's Treasury chief George Osborne was first out of the gate Monday, announcing that all UK financial institutions have ceased business relationships and transactions with Iranian banks, including the Central Bank of Iran.

Osborne says it's the first time the British government has cut an entire country's banking sector off from the U.K.'s financial sector.

"This underlines the severity of the government’s concerns about Iran’s activities," the U.K. government said in a statement.

With files from The Associated Press