Nayef al-Ajmi, the Kuwaiti Minister of Justice, Islamic Endowments and Islamic Affairs, left, and Islamist MP Mohammad al-Hwailah take part in a parliament session at Kuwait's National Assembly. (Yasser Al-Zayyat/AFP/Getty Images)

Kuwait, a U.S. ally whose aid to besieged Syrian civilians has been surpassed only by the United States this year, is also the leading source of funding for al-Qaeda-linked terrorists fighting in Syria’s civil war, according to Obama administration officials.

The amount of money that has flowed from Kuwaiti individuals and through organized charities to Syrian rebel groups such as Jabhat al-Nusra totals in the hundreds of millions of dollars, according to experts whose estimates are endorsed by the Treasury Department.

Until recently, tiny, oil-rich Kuwait avoided public scrutiny as attention to terrorist financing focused more sharply on Saudi Arabia, the United Arab Emirates and Qatar.

But the fact that those countries have made strides in addressing the problem, a senior Treasury official said, has “shed more light on the less forward-leaning steps taken in Kuwait.”

Last month, the administration decided to go public with its concerns. In a remarkably undiplomatic statement that officials said had been cleared at senior levels, Treasury Undersecretary David S. Cohen called Kuwait “the epicenter of fundraising for terrorist groups in Syria.”

Such fundraising was not illegal in Kuwait until last year, when the government took advantage of an unrelated parliamentary boycott to push through a new law.

“Disappointingly, since then there has not been much vigor shown in implementing” a ban on terrorist financing, said the official, who spoke on the condition of anonymity to discuss administration assessments of Kuwait.

The government has also recently established a U.S.-recommended Financial Intelligence Unit, which governments use as clearinghouses for reports of suspicious transaction and to investigate terrorist financing and money laundering.

But “their FIU is still not operating,” according to the Treasury official. “It just sort of calls into question whether there is sufficient will to follow through on the legal steps.”

The Kuwaiti Embassy in Washington did not reply to repeated requests for a response to the U.S. allegations.

Kuwait’s generally low profile in the West rose most prominently in 1991, when the United States sent hundreds of thousands of troops to liberate the constitutional emirate from a seven-month occupation by Saddam Hussein’s Iraq. The 2003 U.S. invasion of Iraq was launched from Kuwait, which subsequently provided the platform for the George W. Bush administration’s Iraq operations and eventually for the U.S. withdrawal.

Unlike other monarchies and autocracies in the region, Kuwait’s politics are relatively open and combative. The executive branch, headed by Emir Sabah Ahmed al-Sabah, frequently clashes with a feisty parliament composed of warring political groups within both the Sunni majority and the Shiite minority.

Unlike other Gulf countries, Kuwait allows broad freedom of association for its 2.7 million citizens, and Sabah’s rule is characterized more by political incorporation than confrontation, according to Elizabeth Dickinson, a journalist in the region whose lengthy analysis of Kuwaiti extremist financing was published in December by the Brookings Institution.

In contrast to highly regulated fundraising elsewhere in the Gulf, many of Kuwait’s charities “are autonomous and regulated with minimal interference” from the government, Dickinson wrote. While some of these groups are widely respected in the philanthropic world for their humanitarian work, “other groups are directly linked to religious sects or organizations” with long histories of support for Salafist movements, which practice a strict form of Islam. At the same time, mosques and private groups often raise money outside the confines of any recognized charity.

In this unregulated stew, fundraising for Syrian rebel groups has become a source of competition among Kuwaiti religious and business leaders, as well as a funnel for contributions from private citizens in other Gulf states with more stringent rules.

Touting their exploits in pictures and videos posted on social media, wealthy and prominent religious Kuwaitis often deliver money and supplies directly to rebel groups such as Jabhat al-Nusra, which the State Department has designated an al-Qaeda affiliate. Many of the groups, which at times have named military brigades after the donors, have their own representatives and liaison entities in Kuwait.

Competition for funds and disputes among benefactors for prominence have become so pervasive that they have contributed to the rise of extremist groups within the Syrian opposition and the inability to organize a critical mass of rebel fighters under a U.S.-approved “moderate” banner, Dickinson wrote.

Senior Treasury delegations have traveled to Kuwait “a dozen times in the last three years” to talk about terror financing issues, said the Treasury official.

Until recently, public U.S. criticism has been tempered by the close diplomatic ties between the two governments and the fact that Kuwait is also by far the largest donor in the Gulf, and fifth in the world, of U.N.-coordinated humanitarian aid to Syria.

This year, with a commitment of $300 million, it is second only to the United States.

The Kuwaiti government has played host to two international humanitarian conferences on Syria at which $3.6 billion was pledged. At the last one, in January, Secretary of State John F. Kerry publicly praised Sabah for his country’s efforts.

In private meetings during the visit, however, Kerry questioned the role of Kuwaiti individuals and charities in sending money to Jabhat al-Nusra and other extremist groups fighting the Syrian government of President Bashar al-Assad.

“We have seen this situation many times,” the Treasury official said, “and it comes in two flavors.” Some of the fundraising efforts “are just outright frauds — what purports to be a charity is really just funneling money” to extremist groups. What is much more common, the official said, are organizations “that to some extent funnel money to blankets and bread and schools, and then money also to supporting terrorist activities. Our steadfast view is that you can’t cleanse the funds that go to support terrorist operations by also giving money to those who are legitimately in need.”

Kuwait’s response, the official said, “is that they’re working on it. They acknowledge that there are steps they need to take.”

Adding to the agitation within the Obama administration is the presence in the Kuwaiti cabinet of a figure who U.S. officials charge is a major terror financier.

The appointment this year of Nayef al-Ajmi as minister for justice and Islamic affairs was a “step in the wrong direction,” Cohen said at a speech to the Washington-based Center for a New American Security. Ajmi, he said, “has a history of promoting jihad. . . . In fact, his image has been featured on fundraising posters” for Jabhat al-Nusra.

The Kuwaiti cabinet expressed outrage. According to KUNA, the Kuwaiti news agency, Minister of Cabinet Affairs Muhammad Abdallah al-Mubarak al-Sabah reiterated Kuwait’s “firm rejection to all forms of terrorism, regardless of its justifications, while reaffirming cooperation with all brotherly and friendly countries and international organizations in the fight against terrorism.”

Ajmi denied promoting jihad or raising money for it. All of his activities, he told the cabinet, were part of Kuwait’s “well-recognized official and unofficial efforts in charitable, religious and humanitarian realms,” KUNA reported.

But this month, Ajmi announced that he had resigned from the government.

Less than a week later, the cabinet said it had rejected his resignation.

Now, the Treasury official said, “we actually don’t know precisely where it stands.”