The Obama administration formally notified Congress yesterday that it is to sell $60bn of weapons to Saudi Arabia, a move designed to boost the US arms industry and help counter growing Iranian power.

The deal, the biggest arms sale in US history, was disclosed last month but the administration, as required by law, has first to seek Congressional approval. Congress has 30 days to block the deal.

"This proposed sale has tremendous significance from a strategic regional perspective," said Andrew Shapiro, the assistant secretary of state for political and military affairs who announced the deal.

"It will send a strong message to countries in the region that we are committed to support the security of our key partners and allies in the Arabian Gulf and broader Middle East. And it will enhance Saudi Arabia's ability to deter and defend against threats to its borders and to its oil infrastructure, which is critical to our economic interests."

The US claims Iran is building a nuclear weapons capability, which Tehran denies. Even without a nuclear weapon, Iran has benefited from the changes in regime in Iraq and Afghanistan, allowing it to expand its influence.

The US is hoping to contain Iran by building up the defences of Saudi Arabia and the neighbouring Gulf states.

In the past, Congress proved difficult over arms sales to Saudi Arabia, reflecting Israeli objections but also because of Osama bin Laden's links to the country. But, focused on the midterm elections, concerned about saving US jobs, and also regarding Iran as a major threat, it is unlikely to create problems.

Sales will include 84 new F-15 fighter jets, upgrades to 70 existing Saudi F-15s, 190 helicopters and a wide array of missiles, bombs and delivery systems, as well as accessories such as night-vision goggles and radar warning systems.