Lausanne, April 1 (IANS/EFE): Russian Foreign Minister Sergey Lavrov has said that the six world powers had reached an accord with Iran on key aspects of its controversial nuclear programme.

Lavrov said on Tuesday that "now it can be announced with sufficient confidence” that an agreement was reached “on the main issues", adding that the technical details of the pact will be worked out between now and the end of June.

Iranian Foreign Minister Mohammed Yavad Zarif told reporters on Tuesday night that the nuclear talks had "advanced enough" on Tuesday and he hoped to begin drafting the pact on Wednesday and "finish the work" on the agreement.

Negotiations for a nuclear deal between Iran and the six world powers -- the US, Britain, China, Russia, France, and Germany -- missed the March 31 deadline for a framework agreement and were extended until Wednesday, according to media reports.

"We've made enough progress in the last days to merit staying until Wednesday. There are several difficult issues still remaining," US state department spokesperson Marie Harf said.

France and Germany had also announced on Tuesday the possibility of pushing the nuclear talks into an extra day.

"We're moving forward, but it's complicated, long and difficult. I think we're going to spend all night here," said French Foreign Minister Laurent Fabius.

Meanwhile, a top Iranian negotiator at the talks acknowledged that several issues had to be resolved before an agreement on Tehran's nuclear programme could be reached, noting that there would be no agreement "until all the issues are resolved".

The international community wants to prevent Iran from acquiring technology and materials for developing a nuclear weapon.

The parties involved in the negotiations had extended the talks in November last year and are hoping for a comprehensive pact by the end of June this year.