Qatar will buy US Patriot missiles for the first time in a major arms deal worth $11 billion, officials said Monday, as Washington awaits a decision by the Gulf state on a lucrative fighter jet contract.

The sale will provide Qatar with roughly 10 batteries for Patriot systems designed to knock out incoming missiles, as well as 24 Apache helicopters and 500 Javelin anti-tank missiles, the US officials, who spoke on condition of anonymity, told AFP.

Qatar was investing in missile defense systems to counter what it sees as the threat from Iran across the Gulf, as Tehran has built up its missile arsenal, officials said.

The weapons deal was the biggest for the United States in 2014 and came as Qatar weighs proposals in a fighter jet competition, with US aerospace firm Boeing vying against British BAE Systems and Dassault Aviation of France.

"It's a good sign," said a senior defense official, referring to the arms sale and the prospects for the fighter jet bidding.

"It's a pretty significant step."

Qatar's minister of state for defense, Major General Hamad bin Ali al-Attiyah, committed to the sale in a signing ceremony Monday in Washington after talks with his American counterpart, Chuck Hagel.

"Today's signing ceremony underscores the strong partnership between the United States and Qatar in the area of security and defense and will help improve our bilateral cooperation across a range of military operations," said Hagel's press secretary, Rear Admiral John Kirby.

It was also the first time Qatar had acquired Patriot missiles, which other Gulf countries such as Kuwait, Saudi Arabia and the United Arab Emirates have purchased in the past.

Qatari Ambassador Mohammed Jaham Al-Kuwari told AFP the missiles and other arms purchased were "defensive" in nature and not directed at any other country.

"As you know our region is going through a lot of instability. What we bought are weapons to defend Qatar," he said.

He said the sale conveyed the importance of Qatar's relationship with the United States adding there were other negotiations that would produce new deals "very soon."

- Building ties with Qatar -

US officials and commanders have long urged their Gulf partners to set up a coordinated missile defense network to counter Iran, but cooperation has been slow in coming.

The weapons would enhance America's security and diplomatic ties to Qatar, the US official said, despite disagreement over Syria and Qatar's assistance to some rebel groups deemed too radical by Washington.

Gulf allies also have voiced concern about US diplomacy with Iran over its nuclear program, fearing the United States may shift away from its long-standing hostility to Tehran.

Officials said the arms sale offered a way of forging closer ties to Qatar and to cultivate relationships with the country's military through training on US-made aircraft and weapons.

"This is an investment in the next generation (of military leaders) ... It's an investment for the long-run," the senior official said.

Meanwhile, Vice President Joe Biden welcomed al-Attiyah at the White House and discussed the deal.

The sale follows a visit to Qatar last December by the US defense secretary, and talks in May between Hagel and Qatari and other Gulf defense chiefs.

Qatar hosts a vital hub for the US military, the Combined Air Operations Center, where officers oversee combat aircraft in Afghanistan and track air traffic across the volatile Middle East.

In his talks with the Qatari minister, Hagel expressed his "appreciation for the support that Qatar provides US forces in the country," Kirby said.

"This is a critically important relationship in the region," said Kirby. "And the secretary is pleased to be able to continue to make it stronger."

- Creating US jobs -

Arms sales also are a way of boosting the US economy, and the deal with Qatar is expected to produce up to 54,000 jobs, according to estimates cited by Pentagon officials.

US defense giants Raytheon and Lockheed Martin manufacture the Patriot missile hardware and Javelin anti-tank missiles, while Boeing produces the AH-64 Apache chopper.

The Patriot missile sale, involving 247 PAC-3 and 117 GEM-T missiles, was worth more than $7 billion. The Apache helicopters and related gear came to more than $3 billion and the Javelin anti-tank missiles over $100 million, according to officials.

Qatar has stepped up weapons purchases as it takes on an increasingly influential role in the region.

The government took the extraordinary step last year of delaying a deadline for proposals by three months in its fighter jet competition after the United States asked for an extension.

The gas-rich kingdom wants to buy a new fleet of modern fighter jets. BAE is offering the Typhoon, while Dassault Aviation hopes Qatar will select the Rafale aircraft. Boeing is promoting F-18 Super Hornets and F-15 fighters for the contract.

It remains unclear when the country will choose a new fighter.