UN negotiations to draft the first international treaty on the multi-billion-dollar arms trade have ended without a deal, with some diplomats blaming the United States for the deadlock.

UN chief Ban Ki-moon said Friday he was "disappointed" that member states failed to clinch an agreement after several years of preparatory work and four weeks of negotiations, calling it a "setback."

But he vowed "steadfast" commitment to obtaining a "robust" arms trade treaty, noting that countries had agreed to pursue negotiations.

"There is already considerable common ground and states can build on the hard work that has been done during these negotiations," he added.

Some diplomats said Washington had refused to vote on the proposed text, saying it needed more time before the midnight deadline and was worried about a pushback from the US Congress.

Russia and other countries followed suit.

"It's the fault of the United States that we failed," a Western diplomat said, requesting anonymity to speak freely about the subject.

"They derailed the process and we will have to wait for the US presidential elections" in November to get out of the impasse, the diplomat added.

But State Department spokeswoman Victoria Nuland said, in a written statement issued late Friday, that the United States supported a second round of negotiations, conducted on the basis of consensus, on the treaty next year.

Nuland noted that while the illicit trafficking in conventional arms was an important national security concern for the United States, Washington did not support a vote at the UN General Assembly on the current text.

"While we sought to conclude this month's negotiations with a Treaty, more time is a reasonable request for such a complex and critical issue," the spokeswoman said. "The current text reflects considerable positive progress, but it needs further review and refinement."

She did not offer any specifics, but said that the United States continued to believe that any arms trade treaty "should require states to develop their own national regulations and controls and strengthen the rule of law regarding arms sales."

Conference chairman Ambassador Roberto Garcia Moritan of Argentina acknowledged that some countries had objected to the final treaty draft. The UN General Assembly, which begins its new session in late September, will decide whether and when there will be more negotiations.

In the end, 90 countries -- including all European Union members, and states from Latin America, the Caribbean and Africa -- signed the text, saying they were "disappointed but... not discouraged" and vowing to soon finalize a treaty based on Moritan's draft.

A consensus of all 193 countries involved in the talks had been required to agree on the accord.

"We always thought this was going be difficult and that this outcome was a possible one," said Moritan.

But he predicted that delegates would have a treaty in their hands "soon."

France's main negotiator, Ambassador Jean-Hugues Simon-Michel, said the failure to reach agreement was the "worst possible scenario" and that diplomats may now have to start all over again.

"The result is rather frustrating and the ball is now in the country of the General Assembly," he told AFP.

Rights groups were also quick to blame the stalemate on the United States, where any treaty on conventional arms sales is vehemently opposed by the powerful gun lobby.

"It was a lack of political will on the part of President (Barack) Obama to take this historic opportunity forward to reduce the effect of the illicit arms trade," said Daryl Kimball, executive director of the Arms Control Association.

He called for "leadership" from Washington, Moscow, London and other major arms exporters and importers, while Oxfam America's senior policy adviser Scott Stedjan blamed the impasse on a lack of "political courage" from Obama.

The White House's failure of courage to press this treaty to conclusion today... is a loss for hundreds of thousands of innocent civilians that die each year from armed violence fueled by the unregulated transfer of arms," said Stedjan.