PARIS — Japanese banks drew on close commercial ties to Qatar when they lent funds that helped Doha pay last year's down payment for Rafale fighter jets and missiles worth €6.3 billion ($6.8 billion), financial specialists said.

A bank loan to Qatar, a nation rich in oil and gas reserves, signaled an economic shift for the Arabian Gulf nation and its strong business ties to Japanese lenders and construction companies.

"Qatar can borrow relatively cheaply on the international bank market as there is huge collateral with the Qatar sovereign fund," said Stéphane Audrand of the consultancy Sylmaris. There is also long-term collateral with Qatar's export energy contracts.

The sovereign fund is valued at $256 billion, according to the Sovereign Wealth Fund Institute, which specializes in institutional investors.

"The relations between Qatar and Japan are unique, focused on construction and LNG," said Sash Tusa, analyst with equity research firm Agency Partners.

The two countries have shared interests, with Japanese companies working on construction projects for the 2022 World Cup soccer tournament in Qatar, which supplies liquefied natural gas to Japan, he said.

Qatar paid the deposit for the Rafale deal Dec. 16, finally putting into effect contracts signed eight months earlier on May 4. A down payment is usually 15 percent of the total amount.

The order included 24 Dassault Aviation fighters and 12 options, and guided weapons from MBDA and Safran's Sagem. The French Air Force will also train Qatari pilots and maintenance personnel.

× Fear of missing out? Sign up for the Early Bird Brief, the defense industry's most comprehensive news and information, straight to your inbox. Thanks for signing up. By giving us your email, you are opting in to the Early Bird Brief.

Japanese banks lent Doha funds for the down payment, said a French executive and a financial specialist who declined to be identified.

Qatar expects its economy this year to fall into a $12.8 billion budgetary deficit, representing 6 percent of gross domestic product, according to the CIA World Factbook. "Low oil prices have dampened the outlook," the report said.

That budgetary upset comes after several years of strong growth, which delivered an estimated 2015 average income of $145,000, the world's highest average income, according to the report. Japan is Qatar's leading trade partner, accounting for 25.3 percent of exports, followed by South Korea's 18.8 percent and India's 12.7 percent.

The Qatari bank loan reflects a steep fall in oil prices. The benchmark Brent crude oil hit a 12-year low of $27.10 on Jan. 20, Reuters reported. The oil price has since risen but that firmer path was partly due to talks by energy producers to freeze production in a bid to prop up prices.

Japanese banks have major business interests in Qatar, which is building transportation and infrastructure projects for the World Cup.

A consortium led by Mitsubishi Heavy Industries won an order estimated at some ¥400 billion (US $61.5 billion) to build a subway in time for the soccer tournament, Japan Times reported Feb. 21. Consortium partner Thales will supply the signaling system, while Hitachi will handle train maintenance.

Last year, Thales also won a security contract for Qatar Hamad port, a large commercial facility which will also be the site for a naval base.

In early January, Qatar closed a $5.5 billion syndicated loan, arranged by six banks including three Japanese lead lenders: Bank of Tokyo-Mitsubishi UFJ, Mizuho, and Sumitomo Mitsui Banking Corp, Reuters reported. Qatar National Bank, Deutsche Bank and Barclays helped arrange the five-year loan, expected to carry a margin of 90 basis points over London Interbank Offered Rate.

A basis point is 1/100 of a percentage point.

Qatar had previously hoped to raise $10 billion with a smaller margin of some 80 basis points, International Financing Review reported.

"The expected slowdown in the Qatari economy is likely to be seen as short-term risk, unlikely to deter Japanese bank lenders, which hold large amounts of cash and are looking for borrowers," Audrand said.

The Japanese banks can offer low-cost financing as they draw on ample funds, with the Bank of Japan injecting cash in a quantitative easing policy in a bid to boost the sagging economy.

Japanese banks have shown some public concern on lending on weapons, as indicated in a ban by Bank of Tokyo-Mitsubishi UFJ on lending to builders of cluster bombs, but there is greater pressure on European lenders.

"European banks are under tight regulatory control on credit risk and deeper scrutiny under corporate social responsibility," Audrand said.

That may have made it hard for French banks to lend to Qatar for the Rafale as there is geopolitical risk, with tension rising with Iran and the Islamic State, he said.

US banks were unlikely to have funded the Qatari order as that would likely displease Boeing, a competitor to Dassault in the fighter market, the financial specialist said.

Qatar seeks acquisition of 73 F-15E Strike Eagle fighters, with 36 in a first tranche, US Senate Foreign Relations Chairman Bob Corker has said. The White House is expected to decide soon whether that deal will go ahead, as the Defense and State Department support for the request.

Doha announced in June a planned order for four Boeing C-17 transports.

Qatar is seen as a large arms market, announcing in 2014 a plan to buy two Airbus A330 multirole tanker transport aircraft and 22 NH90 helicopters.

France hopes to sell a planned DCNS air defense frigate, while Nexter has pitched the Véhicule Blindé de Combat d'Infanterie (VBCI), an infantry fighting vehicle, to Qatar, which is reportedly looking for 200 to 600 units.

The Qatari deal with France includes MBDA Mica air-to-air and Meteor long-range, air-to-air missiles, Scalp cruise missiles, and Sagem's armement air-sol modulaire (AASM), a powered smart bomb, French defense officials said.