Looking for His glorious appearing! Titus 2:13

The European Union - which groups three of the six powers seeking to negotiate a settlement to a decade-old dispute with Iran over its nuclear programme - noted that "some" progress had been made in separate talks between Iran and the International Atomic Energy Agency (IAEA).

But, the 28-nation EU added in a statement to a quarterly meeting of the IAEA's 35-nation governing board, "We call on Iran to provide all the relevant information to the agency, to address fully the substance of all of the agency's concerns and to accelerate its cooperation with the agency."

Canada's ambassador to the Vienna-based IAEA put it more bluntly, saying Iran was using a kind of "salami-sliced, piece-by-piece approach" in its dealings with the U.N. watchdog.

"We are definitely of the view that Iran is moving too slowly to address these long-standing questions. They do need to move faster," Mark Bailey told Reuters.

For several years, the IAEA has been investigating suspicions that Iran may have coordinated efforts to process uranium, test explosives and revamp a ballistic missile cone in a way suitable for a nuclear warhead. Iran says the allegations are false but has offered to help clarify them.

Tehran says its uranium enrichment programme is a peaceful energy project whereas the West fears it is covertly oriented to developing a nuclear weapons capability. Western diplomats have long accused Tehran of stonewalling the IAEA's investigation.

After years of increasing tension with the West - and fears of a new Middle East war breaking out - last June's election of the pragmatist Hassan Rouhani as Iranian president paved the way for a dramatic thaw in relations. However, the sides remain far apart on what a long-term nuclear agreement should look like.