EU foreign ministers will announce the move in Brussels as soon as inspectors from the UN's nuclear watchdog, the IAEA, confirm that Iran has started work on a set of measures to reassure the international community over its nuclear drive, EU sources said Thursday.

The IAEA greenlight is expected in the morning and "a decision and regulation (on lifting the sanctions) will be published the same day."

Under a hard-won deal agreed between Iran and world powers in November, Tehran over the next six months will halt enrichment of uranium over five percent and dilute half of its stockpile of 20-percent enriched uranium in exchange for sanctions relief.

The agreement will see the United States unfreeze billions in Iranian assets while the EU notably suspends a 2012 ban on insuring and transporting Iranian crude oil that caused a more than 50 percent drop in Tehran's oil exports.

European insurers up until then had accounted for 90 percent of coverage for deliveries of Iranian oil anywhere in the world.

The EU also will suspend bans on trade in gold, precious metals and petrochemical products while increasing a ceiling on financial transfers not related to remaining sanctions.

Like the United States, the EU has promised to impose no new sanctions in the next six months, seen as the first stage in efforts to find a lasting solution over fears that Iran is developing a nuclear bomb.

An EU source therefore stressed that any new contracts struck with Iranian firms should not go beyond the six-month period. "Contracts should be executed during this period," added the source, who asked not to be identified.

"We want this to work," the source said.

If all goes to plan, EU firms from Monday will be able to insure or transport Iranian crude oil to its six customers, China, India, Japan, Korea, Turkey and Taiwan.

But the powers that negotiated the deal -- the United States, France, Britain, Russia, China and Germany -- have maintained many of the sanctions that have hobbled the Iranian economy.