DUBAI - Iran said on Wednesday a delay by world powers in agreeing to preparatory talks has thrown doubt on the next round of negotiations over the Islamic Republic's disputed nuclear program, the state news agency IRNA reported.Iran's ISNA news agency said on Tuesday Tehran had written twice to Britain, France, Russia, China, the United States and Germany - otherwise known as the P5+1 - seeking preparatory meetings before talks in Moscow, but had yet to hear back.A spokeswoman for Ashton said she would contact Jalili before the planned Moscow negotiations but saw no need for further preparatory meetings."We have made it very clear that preparatory work is ongoing and political issues need to be dealt with on political level. That's why the high representative will reach out to Jalili and this will happen before the next round in Moscow," Ashton's spokeswoman Maja Kocijancic said."We are not against technical meetings in principle but timing is not really right for that," she said.It is unclear what Iran aims to gain from the proposed preparatory talks. Western diplomats have often accused Tehran of seeking to buy time for its nuclear activities by trying to engage in talks about process rather than substance, without real intention of making any concrete concessions.Western nations suspect that the Islamic Republic's higher-grade uranium enrichment is part of a clandestine program to develop the material and components needed for a capacity to produce nuclear arms. Iran denies this.Negotiations are due to resume in Moscow on June 18, almost a month after the last round in Baghdad.On Tuesday, an adviser to Iran's supreme leader was quoted as saying the talks could have a positive outcome if world powers recognized Iran's "nuclear rights"."The other side's delaya in meeting deputies and experts throws doubt and ambiguity on their readiness for successful talks," said Iran's chief negotiator Saeed Jalili in a letter to EU foreign policy chief Catherine Ashton, according to IRNA.