The talks between the five permanent members of the Security Council plus Germany will seek to build on a meeting held Monday in London at the level of foreign ministry directors.
Britain, China, France, Germany, Russia and the United States will try to hammer out a second resolution to be presented to the UN Security Council on tougher sanctions against Tehran.
The countries are to be represented by senior policy officials.
French Foreign Minister Philippe Douste-Blazy earlier this week sounded optimistic, saying prospects for a quick agreement on new sanctions resolution were good.
Washington is also awaiting the outcome of the six-way contacts after a report from the UN nuclear watchdog agency, the IAEA, last week said that Iran had not halted, and in fact was expanding, its uranium enrichment programme.
“We hope at that point that they can actually come to agreement on the elements of the resolution.
(…) You would proceed from that point in finishing up negotiations on the actual text of the resolution,” said US State Department spokesman Sean McCormack on Monday.
The United States and some other western powers believe Iran is pursuing a nuclear weapons capability.
Iran however has denied seeking nuclear weapons, and asserts it has a right to a peaceful nuclear program.
In London, a Foreign Office spokeswoman said there would be contacts on the steps to be taken to confront Iran but declined to give specific details.