Iran is negotiating with the United States as part of a "constructive engagement" with the world community.

President Hassan Rouhani said it is seeking actions from the US to back up its words.

Mr Rouhani, speaking at the World Economic Forum in Davos, also said relations with Europe will be normalised as an interim nuclear accord is implemented.

Addressing about 2,500 global business and political leaders, he invited European companies, especially major energy groups, to seize economic opportunities in Iran.

"The Islamic Republic of Iran is prepared to engage in constructive cooperation for promoting global energy security, drawing on its vast oil and gas resources," he said.

Underscoring that pitch, he held a private meeting with oil and gas executives at a hotel in the Swiss resort before his speech.

A deal with six major powers, including the US, to restrict Iran's disputed nuclear programme in exchange for a partial easing of economic sanctions entered into force this week.

"I hereby announce that one of the theoretical and practical priorities of my government is constructive engagement with the world," Mr Rouhani said.

However, most sanctions, including a severe squeeze on access to the international financial system, remain in force and the US has stressed Western companies should not regard Iran as "open for business".

Mr Rouhani promised to pursue a foreign policy of "prudence and moderation" to revive the battered economy.

He called for cooperation with all Iran's neighbours but did not mention Gulf rival Saudi Arabia by name and refused, when pressed twice, to include Israel among states with which Iran sought friendly relations.

Iran wanted friendship and cooperation with "all the countries which the Islamic Republic of Iran has recognised", he said.

Mr Rouhani repeated Iran's standard pledge not to seek nuclear weapons and said his government was willing to accept all safeguards and inspections of the UN nuclear agency, provided it was not subjected to "discrimination".

Western countries believe the atomic effort is aimed at developing a military capability.

"We never sought and will never seek nuclear weapons," the president said. "I declare that a nuclear weapon has no place in our security strategy."

Mr Rouhani said Iran had a strong will to clinch a permanent settlement to the nuclear issue while the six-month interim accord is in force, but he said other countries might succumb to "pressure from other parties" - a veiled reference to Israel - not to reach a deal.

In a foretaste of tough negotiations on a long-term agreement, he said: "Iran will not accept any obstacles to its scientific progress."