Kerry: difficult decisions must be made 'soon'

Speaking in Vienna, the US Secretary of State said all sides "believed they were making progress towards a comprehensive deal," saying it was important a deal was made that could "withstand the test of time."

But Kerry cautioned that they wouldl "not sit at the negotiating table forever," and if difficult decisions had to be made, they should be made as soon as possible.

His comments came as the international community upped the pressure on Iran as they tried desperately to find a solution over the nation's nuclear capabilities, in return for easing tough sanctions.

Earlier in the day Kerry tweeted that "difficult issues" were being discussed, with all parties "working diligently to see if agreement possible." Kerry has been in the Austrian capital since June 26, with various foreign counterparts coming and going. Iran's Foreign Minister Javad Zarif has been holding one-on-one meetings as well as wider discussions with officials. All sides have agreed that progress has been made during recent days, with most of the final wording of the agreement having been written. But negotiators remain at odds over issues such as a UN investigation into retrospective allegations that Iran sought to develop nuclear weapons, while the Islamic Republic is demanding a UN arms embargo be lifted.

Political will?

Speaking in the Russian city of Ufa, Russian Foreign Minister Sergei Lavrov backed Iran's request to drop the embargo, but said no "insurmountable problems" remained to stall discussions. His deputy, Sergei Ryabkob, also voiced optimism, saying a deal could occur "in the coming hours if the sides shows the political will."

Speaking on Wednesday, US spokeswoman Marie Harf told television network CNN they would not give up until the agreement satisfied all parties involved, and that the current accord doesn't yet "have all the assurances we need, it doesn't meet our bottom line, so we are taking more time."

Negotiators from the P5+1 group - the US, the UK, China, France and Russia, plus Germany - held back-to-back meetings on Thursday, in a race against time to meet the latest deadline on Friday. Two previous deadlines have already been missed during the current round of talks. The US congress says it hopes to receive the text early in the morning Vienna time in order to shorten the amount of time needed to review it.

Sources close to Iran said arrangements were being made for the likelihood of remaining in Vienna until Monday. Raising hopes a deal was close, a video conference was held between Kerry and the US delegation with US President Barack Obama on Wednesday, but no details were given.

an/kms (dpa, Reuters, AFP, AP)