The UN Security Council on Tuesday expressed its desire to better enforce sanctions against Iran and reiterated its concern about the country's alleged plans to build nuclear weapons.

The United Nations has passed four rounds of sanctions against Iran for its refusal to halt uranium enrichment, including a global arms embargo. Western nations accuse Iran of seeking a nuclear bomb while Iran insists its enrichment program is for purely civilian purposes.

Rosemary DiCarlo, deputy US ambassador to the UN, said Iran refuses to discuss possible military dimensions to its nuclear program.

She noted that the head of the International Atomic Energy Agency recently said he was unable "to conclude that all nuclear material in Iran is in peaceful activities."

"This conclusion is cause for grave concern for this Council and for the international community at large," DiCarlo said.

It's critical that countries better enforce the sanctions, said DiCarlo, adding that the sanctions committee "should be prepared to act quickly ... to take additional steps in line with its program of work to tighten sanctions enforcement."

"Our goal remains to prevent Iran from developing nuclear weapons. We remain committed to working closely with our partners in this Council and the international community toward that goal," she said.

Over the past year a growing number of cases of weapons and explosives seizures involving Iran have been brought before the UN sanctions committee.

Last week, diplomats revealed that South Korea and Singapore had intercepted suspected nuclear and weapons materials bound for Iran that breach UN sanctions imposed on the Islamic republic.

The two seizures, made in the past six months but only revealed recently, add to a growing list of alleged Iranian attempts to breach an international arms embargo.

Martin Briens, France's deputy ambassador to the UN, said that violations are adding up.

"We also noted with concern the evidence relating to the seizure of Iranian arms bound for the Taliban," he said.

This month, Britain said that arms seized by its special forces in Afghanistan on February 5 were being supplied by Iran to the Taliban militia fighting international forces.

The French diplomat also expressed concern about Iran's recent announcement that it conducted rocket testing.

Germany's ambassador, Peter Wittig, said the efficiency of the measures "could be improved" by better informing countries about the sanctions already in place, and how they're applied.

"Iran continues to pursue (uranium) enrichment activities and is, once again, in violation of its international obligations," Wittig said.

"We remain committed to finding a long-lasting peaceful solution to the Iranian nuclear program," the German ambassador said. "We call on Iran to reconsider its intransigent attitude to return to the negotiation table in good faith."

Russia's UN ambassador Vitaly Churkin said Russia enforces "all elements of the sanctions regime and we think all the members of the international community need to strictly implement Security Council resolutions to that respect."

At the last Security Council debate on the Iran sanctions, Britain called for new Iranian individuals and entities to be added to sanctions lists. France said there should be a detailed investigation of Iran's sanctions-busting.