Secretary of Iran's Supreme National Security Council (SNSC) Saeed Jalili has warned the EU in a letter on Thursday that adopting any illegitimate measures will have "repercussions" on the prospects of nuclear talks between Tehran and the west.

In a letter addressed to EU foreign policy Chief Catherine Ashton who represents the P5+1 group on Thursday, Iran's top nuclear negotiator, Saeed Jalili warned the West of repercussions of taking action which is far removed from the logic in the talks and of using illegal methods against the Iranian nation."

The top Iranian negotiator wrote that "if the constructive talks are damaged, the responsibility will be with the party that is implementing illegal tools instead of logic in the negotiations."

Saeed Jalili stated that Iran stands ready to share initiatives that can make the talks a success and move them forward.

But he added that successful talks are only possible in the framework of cooperation and building trust," Press TV said.

According to AFP, the letter was sent on the day the United States ratcheted up sanctions on foreign companies doing business with Iran's central bank, and just ahead of the full implementation on Sunday of an EU-wide embargo on Iran's oil exports.