An interim deal on Iran's nuclear program is due to enter into force in a few hours' time, BBC News reports.
The process will begin with the UN nuclear watchdog, the IAEA, confirming that Tehran has curbed some of its high-level uranium enrichment. This should pave the way for partial suspension of EU and US sanctions.
It is expected that by the end of the day Iran should be able to resume petrochemical exports and trade in gold, worth billions of dollars.
The interim deal was agreed in November during talks with the five permanent members of the UN Security Council – U.S., Russia, China, France and Britain - plus Germany.
The West accuses Iran of seeking nuclear weapons, but Tehran denies the claim, saying its program is solely for peaceful purposes.
Later in the day, inspectors from the IAEA are likely to verify the deal's implementation by Tehran. That conclusion is then expected to be wired to Brussels, the BBC says.
There ministers - including UK Foreign Secretary William Hague - are expected to lead their EU counterparts in voting unanimously in favor of a partial lifting of the sanctions which have been in place against Iran since 2006.
Within an hour or two restrictions on Iran's trade would then be lifted.
On Sunday, Jan 19, Iranian Foreign Minister Mohammad Javad Zarif said he hoped for "positive results for the country, as well as regional and global peace and security".
Under the terms of the agreement, Iran has agreed to halt enrichment of uranium above 5% purity, and "neutralize" its stockpile of near-20%-enriched uranium.
In return, the world powers agreed to suspend certain sanctions on trade in gold and precious metals, Iran's automotive sector, and its petrochemical exports.
Senior US administration officials told the BBC last week that some of the sticking points that had been resolved in the past weeks centred on how often inspectors would be allowed to visit Iran's nuclear sites.
Officials said as a result of the deal: From Jan 20, Iran will start diluting its stockpile of 20%-enriched uranium; All 20%-enriched uranium will be gone within six months; Daily access will be provided to the Fordow uranium enrichment site near the holy city of Qom; Monthly inspections will be allowed at the Arak heavy water reactor.