The Pentagon informed Congress on Monday it plans to sell 24 Apache attack helicopters to Iraq in a deal worth $4.8 billion, officials said, as Baghdad battles anti-government militants.

Iraqi Prime Minister Nuri al-Maliki's government has asked Washington for weapons and intelligence as it takes on Al-Qaeda-linked fighters in Anbar province but it remains unclear if US lawmakers will approve the proposed package.

Congress has 15 days to raise objections to the planned arms sale, which also includes 480 Hellfire missiles and associated radar and navigation systems, according to the Defense Security Cooperation Agency (DSCA), which oversees foreign arms sales.

The Pentagon also had separately notified Congress of plans to lease six Apache choppers to train Iraqi pilots.

"This proposed sale supports the strategic interests of the United States by providing Iraq with a critical capability to protect itself from terrorist and conventional threats, to enhance the protection of key oil infrastructure and platforms, and to reinforce Iraqi sovereignty," the DSCA said.

The Boeing AH-64 helicopters will help provide Iraqi forces with "close air support, armed reconnaissance and anti-tank warfare missions," it said.

For weeks, parts of Ramadi and all of Fallujah in western Iraq have been in the hands of anti-government fighters, including members of the Al-Qaeda-linked Islamic State of Iraq and the Levant (ISIL).

The militants' recent gains have marked the first time they have openly controlled Iraqi cities since the 2003 US-led invasion.

US President Barack Obama and other foreign leaders have urged Baghdad to take political steps to undercut support for the militants, against whom the Shiite-led government has taken a hard line, launching a massive operation.

Some lawmakers object to selling more arms to Iraq due to reports Baghdad is allowing Iran to use its airspace to help the Syrian regime. They also worry the Iraqi government will use the helicopters and other weapons to target political enemies instead of only suspected Al-Qaeda extremists.