EU foreign policy chief Javier Solana on Saturday presented Iran a modified package of incentives to suspend uranium enrichment, as Iran reaffirmed its refusal to do so, raising the prospect of tougher sanctions against the Islamic nation. Solana said he hoped for a positive response from Iran on the package of economic, technological and political incentives, which was drawn up by the five permanent members of the UN Security Council plus Germany. But Iran's government spokesman, Gholam Hossein Elham, immediately said Iran won't accept the package if it asks Iran to suspend uranium enrichment, a process that can produce nuclear fuel to generate electricity or power a bomb. "Preconditions can't be raised for any halt or suspension," the official news agency IRNA quoted Elham as saying Saturday. The US and many other Western nations have accused Iran of using its nuclear program as cover for potential weapons development - a claim denied by Teheran, which says it is exclusively focused on generating electricity. The UN Security Council has passed three sets of sanctions against Iran for its failure to suspend enrichment, and the US and several of its European allies are pushing for tougher measures if Teheran turns down the latest incentive package. The proposal presented Saturday was accompanied by a letter signed by Solana and the foreign ministers of the United States, Britain, France, Russia, China and Germany. The letter, which was made available to reporters along with a copy of the proposal, said it was "possible to change the present state of affairs" provided Iran halts sensitive nuclear work. "Formal negotiations can start as soon as Iran's enrichment-related and reprocessing activities are suspended," the letter said. Solana reiterated this message in a press conference after his talks with Iranian officials, saying "we continue to ask for ... suspension during the time of negotiations and we will see the outcome of the negotiations." "We are hoping for an early and a positive answer" to the proposal, added Solana, who met with Iranian Foreign Minister Manouchehr Mottaki and top nuclear negotiator Saeed Jalili on Saturday. After receiving the package, Mottaki said Iran's response will hinge on what the world powers have to say about Teheran's own set of proposals presented last month. "We are waiting to receive specific views of the 5+1 to Iran's proposals," said Mottaki in a statement, referring to the five permanent members of the UN Security Council plus Germany that have called on Iran to halt its uranium enrichment program or face tougher sanctions. "It is natural that Iran's response to the 5+1 package will take into consideration the reply given by 5+1 to Iran's package," Mottaki added. Mottaki's comments are believed to reflect Iran's displeasure with the failure of the world powers to welcome Iran's proposals on a range of issues, such as drug control, environmental conservation as well as the nuclear issue. Teheran's proposal does not offer to give up uranium enrichment. Solana said later that he presented Iran with an answer from the group on Iran's proposal but did not provide any details. US President George W. Bush, in his final tour of Europe before stepping down in seven months, said Saturday that Iran has isolated its people and put the world in danger by rejecting the offer. He was referring to comments by Elham who rejected any suspension of uranium enrichment Saturday. "I'm disappointed that the leaders rejected this generous offer out of hand," Bush said. "It's an indication to the Iranian people that their leadership is willing to isolate them further." French President Nicolas Sarkozy took the same approach as Bush at a joint news conference. He said the Iranian people "deserve better than the impasse into which some of their leaders are leading them." Sarkozy called a nuclear Iran an "unacceptable menace to the stability of the world" and his Foreign Minister Bernard Kouchner told the Saudi daily Okaz in a Saturday interview, that new sanctions would be imposed on Iran if it turned down the incentive package. The six nations first offered a package of economic, technological and political incentives to Teheran nearly two years ago on condition that it suspend enrichment. The repackaged incentives were agreed on last month in what diplomats called mainly cosmetic changes to the original 2006 offer, while maintaining the threat of further UN sanctions. The new package offers to help Iran develop a peaceful nuclear energy program and improve economic and diplomatic relations with the six countries and the EU if Teheran agrees to suspend uranium enrichment.