North Korea supplied several shipments of missile components to Iran during recent nuclear talks and the transfers appear to violate United Nations sanctions on both countries, according to U.S. intelligence officials.

Since September more than two shipments of missile parts have been monitored by U.S. intelligence agencies as they transited from North Korea to Iran, said officials familiar with intelligence reports who spoke on condition of anonymity.

Details of the arms shipments were included in President Obama’s daily intelligence briefings and officials suggested information about the transfers was kept secret from the United Nations, which is in charge of monitoring sanctions violations.

Critics of the U.S.-led nuclear framework agreement reached in Switzerland earlier this month have said one major deficiency of the accord is its failure to address Iran’s missile program, considered a key nuclear delivery system for the Islamist regime.

CIA spokesman Ryan Trapani declined to comment on the missile component shipments, citing a policy of not discussing classified information.

But other officials said the transfers included goods covered by the Missile Technology Control Regime, a voluntary agreement among 34 nations that limits transfers of missiles and components of systems with ranges of greater than 186 miles.

One official said the transfers between North Korea and Iran included large diameter engines, which could be used for a future Iranian long-range missile system.

The United Nations Security Council in June 2010 imposed sanctions on Iran for its illegal uranium enrichment program. The sanctions prohibit Iran from purchasing ballistic missile goods and are aimed at blocking Iran from acquiring "technology related to ballistic missiles capable of delivering nuclear weapons."

U.S. officials said the transfers carried out since September appear to be covered by the sanctions.

Other details of the transfers could not be learned. However, U.S. intelligence agencies in the past have identified Iran’s Islamic Republic of Iran

Shipping Lines (IRISL) as the main shipper involved in transferring ballistic missile-related materials.

A U.S. report to the United Nations sanctions committee in 2010 stated that Washington closely cooperates with partner states in monitoring IRISL and other Iranian merchant shipping companies that pass through airports, seaports, and other international borders. The report said the United States takes "steps to prevent transfers of items prohibited by this and by previous Iran-related resolutions."

The American efforts to block arms transfers are carried out under the George W. Bush administration’s international Proliferation Security Initiative.

A classified State Department cable from October 2009 reveals that Iran is one of North Korea’s key missile customers.

The cable, made public by Wikileaks, states that since the 1980s North Korea has provided Iran with complete Scud missiles and production technology used in developing 620-mile-range Nodong missiles.

Additionally, North Korea also supplied Iran with a medium-range missile called the BM-25 that is a variant of the North Korean Musudan missile.

"This technology would provide Iran with more advanced missile technology than currently used in its Shahab-series of ballistic missiles and could form the basis for future Iranian missile and [space launch vehicle] designs."

"Pyongyang's assistance to Iran's [space launch vehicle] program suggests that North Korea and Iran may also be cooperating on the development of long-range ballistic missiles."

A second cable from September 2009 states that Iran’s Safir rocket uses missile steering engines likely provided by North Korea that are based on Soviet-era SS-N-6 submarine launched ballistic missiles.

That technology transfer was significant because it has allowed Iran to develop a self-igniting missile propellant that the cable said "could significantly enhance Tehran’s ability to develop a new generation of more-advanced ballistic missiles."

"All of these technologies, demonstrated in the Safir [space launch vehicle] are critical to the development of long-range ballistic missiles and highlight the possibility of Iran using the Safir as a platform to further its ballistic missile development."

A spokesman for Spain’s mission to the United Nations, currently in charge of the world body’s sanctions committee, said the committee has not received any communications from the United States since Spain took charge of the panel in January.

Security and arms control analysts said the North Korean missile components shipped to Iran highlight the deficiencies of the Iran framework agreement announced earlier this month.

The framework is under fire from Congress. The Senate Foreign Relations Committee on Tuesday held a meeting to discuss legislation that would require the administration to submit a final Iran nuclear agreement to the Senate.

The committee voted to approve a bipartisan bill that would require Senate approval for any final Iran nuclear agreement. The legislation would block the administration from lifting any sanctions on Iran until after Congress approves the formal accord that is to be worked out before June 30. The White House has threatened to veto the legislation if it passes both the House and Senate.

Joseph DeTrani, former director of the National Counterproliferation Center, a U.S. intelligence agency, said North Korea has maintained "close and long term" relations with Iran on the transfer of missiles and missile-related technology.

"U.N. Security Council resolutions prohibit this type of activity, and continued missile-related transfers from North Korea to Iran would be in violation of these Security Council resolutions," said DeTrani, a former CIA officer and special envoy to North Korea nuclear talks.

"The Proliferation Security Initiative (PSI), comprised of over 100 countries, was established to monitor such activities and assist with the interdiction of such proscribed transfers. To date, PSI has been relatively successful," he added.

Former United Nations Ambassador John Bolton also said the missile transfers would violate U.N. sanctions on both Iran and North Korea.

U.N. sanctions imposed on Pyongyang in 2009 for North Korea’s nuclear and missile tests prohibit the export of missiles and related technology.

"And if the violation was suppressed within the U.S. government, it would be only too typical of decades of practice," Bolton said. "Sadly, it would also foreshadow how hard it would be to get honest reports made public once Iran starts violating any deal."

Bolton, who also served as undersecretary of state for arms control in the George W. Bush administration, said he remembers the difficulty of getting the bureaucracy to use the word "violation" instead of diplomatic euphemisms such as "non-compliance."

Former CIA analyst Fred Fleitz also criticized the administration for not publicizing the sanctions violations.

"While it may seem outrageous that the Obama administration would look the other way on missile shipments from North Korea to Iran during the Iran nuclear talks, it doesn’t surprise me at all," Fleitz said.

"The Obama administration has excluded all non-nuclear Iranian belligerent and illegal activities from its nuclear diplomacy with Iran," he said. "Iran’s ballistic missile program has been deliberately left out of the talks even though these missiles are being developed as nuclear weapon delivery systems."

Fleitz said Iran’s role as a state sponsor of terrorism also has been excluded from the nuclear talks, along with Iranian aggression and subversion in the Middle East.

"Since the administration has overlooked this long list of belligerent and illegal Iranian behavior during the Iran talks, it’s no surprise it ignored missile shipments to Iran from North Korea," he added.

Thomas Moore, a former Senate Foreign Relations Committee arms control specialist, said if the recent missile component transfers are confirmed, "it certainly points out the glaring omission present in the Iran deal: the total lack of anything on its missile threat."

"If true, allowing proliferation with no response other than to lead from behind or reward it, let alone bury information about it, is to defeat the object and purpose of the global nonproliferation regime—the only regime Obama may end up changing in favor of those in Tehran, Havana and Pyongyang," Moore said.

Henry Sokolski, head of the Nonproliferation Policy Education Center, also said the latest report of North Korean missile technology exports to Iran "more than suggests why the administration had to back away from securing any ballistic missile limits in its negotiations" with Tehran.

White House National Security Council spokeswoman Bernadette Meehan declined to comment. State Department spokeswoman Marie Harf did not return emails seeking comment.