The source said the talks between Javier Solana and Ali Larijani began in the morning and have continued into the evening.
Earlier it was reported that a meeting between top EU and Iranian envoys in Spain late Thursday ended with little progress in resolving a dispute over Tehran's controversial uranium enrichment program, but the negotiators agreed to resume discussions within two weeks.
EU High Representative on the Common Foreign and Security Policy Solana said the most important outcome of the talks with Larijani, head of Iran's Supreme National Security Council, was an agreement to meet again.
"We are seeking a new impetus for negotiations and we agreed to meet again the week after next," Solana said, adding the talks were held in a "positive good atmosphere."
The Islamic Republic has refused to suspend its nuclear program, which Western countries suspect is aimed at making nuclear weapons, whereas Tehran insists it needs nuclear technology for electricity generation only.
Iran failed to halt its uranium enrichment activities by the May 24 deadline set by the UN Security Council, and further expanded its controversial program. Tehran now faces more stringent international sanctions.
