The European Union looks set to push India at a summit Friday to use its commercial and diplomatic influence to try to bring Iran back to the negotiating table over its disputed nuclear programme.

India has a good relationship with Iran, which is the South Asian nation's second-largest oil supplier after Saudi Arabia, providing 12 percent of India's crude needs at an annual cost of around $12.7 billion.

The energy-hungry country has continued to buy oil from Iran despite an intensifying US- and EU-led sanction campaign to smother Tehran's vital oil exports until it abandons its suspected drive to build nuclear weapons.

In an interview with the Times of India ahead of the one-day EU-India summit in New Delhi, European Council president Herman Van Rompuy suggested India's refusal to join the sanctions programme could be exploited constructively.

"I plan to ask Indian leaders to apply their considerable leverage to Iran and help in convincing the Iranian leadership to give up their sensitive nuclear programme and return to the negotiating table," Van Rompuy said.

Indian foreign policy experts have previously suggested New Delhi could act as an interlocutor with Iran to help the world community engage with the Islamic republic over its nuclear goals, which Tehran maintains are peaceful.

Defending its decision to continue oil purchases from Tehran, India argues it is bound only by UN sanctions on Iran, not embargoes imposed by other countries.

"We can't determine what Indian companies do," acknowledged EU ambassador to India Joao Cravinho.

During the summit -- attended by Van Rompuy, EU Commission President Jose Manuel Barroso and Indian Prime Minister Manmohan Singh -- the two sides will also focus on bridging differences holding up a long-delayed free trade pact.

"We hope to bring a package together that will get the political blessing from the EU president and Prime Minister Singh," Cravinho told AFP.

Such a package would allow negotiators to move into the final lap of talks for an accord that could be wrapped up in the second half of 2012, embracing 1.8 billion people or nearly a quarter of the global population, Cravinho said.

Intense negotiations have been under way for weeks with both sides "working on the nature of trade-offs needed to reach a political agreement", he added.

Indian Commerce Minister Anand Sharma said talks were in the "final stage" but a "few gaps" remained to be closed, while a senior Indian government official, who could not be named, said New Delhi hoped for a "significant announcement."

Deadlines for concluding the deal, under discussion since 2007, have been repeatedly missed with the EU pressing India to cut duties on cars, wines and spirits.

In turn India is seeking greater EU market access for its farm products, textiles and IT services.

The EU is also keen on making new inroads into India's banking and retail sectors, while India wants the EU to allow freer movement of its professionals in the 27-nation bloc.

"The EU-India free trade agreement is one of the biggest and most ambitious free trade agreements ever negotiated," said Cravinho.

India has already struck free trade deals with Japan, Malaysia and South Korea, while the EU is in trade liberalisation talks with Canada and Japan, among other countries.