Iran has given its response to an offer of incentives for suspending uranium enrichment, Iranian state media report.
They say the response was delivered to EU foreign policy chief Javier Solana, without giving any further details.
The incentives package from China, the EU, France, Russia, the UK and US was offered to Iran by Mr Solana in June.
He also asked Iran to accept a six-week freeze on further developments on its controversial programme, in return for a similar freeze on new UN sanctions.
The UN Security Council approved a third round of sanctions against Iran over the issue in March 2008.
Separately, the EU also imposed new sanctions on Iran in June.
Tehran denies Western claims that it is seeking to build a nuclear weapon, saying its programme is peaceful.
It has repeatedly rejected demands to halt enriching uranium, which can be used as fuel for power plants or material for weapons if refined to a greater degree.
Incentives
Tehran's response was delivered to Mr Solana by Iran's ambassador in Belgium, Iran's official Irna news agency said, quoting an unnamed Iranian official.
The official said the response was signed by Iranian Foreign Minister Manoucher Mottaki.
Iran's state TV also said that Tehran's top nuclear negotiator Saeed Jalili had a telephone conversation with Mr Solana on Friday.
Mr Solana's office has so far not confirmed that Iran's response to the European package was delivered.
The incentives package builds on a previous offer of 2006 and says that if Iran suspends uranium enrichment, then talks can start about a long-term agreement.
On offer is recognition of Iran's right to develop nuclear energy for peaceful purposes and the treatment of Iran in "the same manner" as other states under the Nuclear Non-Proliferation Treaty.
Iran would get help with developing nuclear power stations and be guaranteed fuel for them.
It would also be offered trade concessions, including the possible lifting of US sanctions preventing it from buying new civilian aircraft and parts.
