Iran's top nuclear negotiator said Saturday Iran and the European Union (EU) had failed to reach agreements on "objective guarantees" in their nuclear talks wrapped up on Friday, state TV reported.

"As to Iran's nuclear issue, the two sides have not set a clear definition about the objective guarantees," top negotiator Sirus Nasseri was quoted as saying.

"Although we had made great efforts, we failed to reach a conclusion, and there are still ambiguities over some key issues," Nasseri said.

The EU has asked Tehran to provide "objective guarantees" to prove the peaceful nature of its nuclear activities.

Tehran insisted the "objective guarantees" should not be defined as permanent halt of its uranium enrichment activities.

Nasseri said during the latest round of talks Iran had reiterated its basic position that it would continue building nuclear reactor.

"The only guarantee we can provide is that we will never pursue military use of nuclear technology," Nasseri added.

Iran and the EU on Friday concluded the fourth round of nuclear negotiations in Geneva.

A report signed by foreign ministers of Britain, France and Germany in Brussels earlier Friday threatened to support a referral of Iran's nuclear case to the UN Security Council if talks fail.

The United States, accusing Iran of developing secret nuclear weapons, has urged to refer the country's case to the UN Security Council.

Tehran denied the accusation, terming it politically motivated.

Source: Xinhua