This is a relationship that both the US and Pakistan frown at for different reasons, but that has not stopped India and Iran to explore new frontiers of bilateral partnership.

Iranian Foreign Minister Kamal Kharrazi concluded a three-day visit to India Tuesday at a difficult time internationally for Tehran, but he has more than one reason to be happy with the outcome.

A sympathetic Indian leadership not only assured him of India's cooperation and understanding in Iran's hour of crisis as it faces mounting US pressure over its "nuclear ambitions," it also promised to continue India's assistance for various development projects in Iran.

Apart from cultural and civilisational links and shared views on international developments, there are strong commercial and economic interests that underpin India-Iran ties. 

For India, Iran is a promising supplier of oil and gas. Not only Iran is the second largest producer of oil among the Organisation of Petroleum Exporting Countries (OPEC), it also has the world's second largest natural gas reserves.

While cash-strapped Iran desperately needs to export its gas, India, with its energy requirements galloping with a rapidly growing economy, wants assured sources of supply of the critical fuel.

A proposed trilateral pipeline is envisaged to carry the gas from Iran's South Pars fields through Pakistan and deliver to India at its border on a "pay and take" basis.

India has also signed a memorandum of understanding with Iran and Turkmenistan to facilitate Indian exports to the Central Asian countries by rail across Iranian territory from Bandar Abbas port.

India is also helping in developing the strategic Chabahar port in southeastern Iran and linking it by a railway line with the city of Bam. The port will provide alternative access to Afghanistan through a 218 km road being constructed by Indian engineers from Delaram to Zaranj.

Pakistan's refusal to allow its territory for movement of goods between India and Afghanistan caused Kabul to try the Iran-Indian option and allow Afghan exporters to use the Chabahar port. Afghan vehicles have been given full transit rights to use the Iranian road system for transporting goods.
 
Similarly, India, Iran and Afghanistan have signed an agreement to give Indian goods, heading for Central Asia and Afghanistan, preferential treatment and tariff reductions at Chabahar.

While the US is not happy with the growing India-Iran ties, Britain, and perhaps the European Union, see it differently.

British Foreign Secretary Jack Straw, who was in India ahead of Kharrazi's visit, indicated that unlike during the Iraq campaign, Britain is not willing to toe the US line on Iran.
 
In a clear support for diplomatic rather than military moves, he said Britain viewed the Iran-India engagement as "very, very important" because New Delhi could influence Iran on its controversial nuclear programme.

"India is emerging as a big global player in diplomatic affairs as well as economic (matters). I have talked before to the Indian government on Iran and India has played a very constructive role behind the scenes," Straw said in a published interview.

"Whatever the US pressure, India-Iran relations will continue to grow. Iran is strategically very important for us and a major source of oil and gas supplies," said G. Parthasarthy, a former envoy to Pakistan.

Pakistan had viewed the growing ties between India and Iran as part of an Indian policy of "encirclement" by forging close ties with Afghanistan and the Central Asian countries bordering it.

But the trilateral pipeline project to bring Iranian natural gas to India via Pakistan that the three countries agreed to earlier this month after years of negotiations may help remove some of Islamabad's misgivings.

The traditionally strong ties between India and Iran had come under strain in the late seventies after the Iranian revolution that saw Tehran increasingly taking a strident fundamentalist line. Also, it strongly criticised events like the demolition of the Babri mosque in Ayodhya.

India's failure to oppose the Soviet intervention in Afghanistan and condemn Iraq president Saddam Hussein's invasion of Kuwait had further affected the ties.

Normal relations were restored following New Delhi's initiative in the nineties to remove misunderstandings, leading to a landmark visit by prime minister P.V. Narasimha Rao to Tehran in 1993 and a visit by President Rafsanjani to Delhi two years later.

Those ties were cemented by prime minister Atal Bihari Vajpayee's visit to Iran in 2001 that is considered a watershed in bilateral ties.

"We support the cooperation of Russia and India and the programmes of North-South Corridor. Iran is prepared to cooperate with India on information technology and welcomes the presence of India and other friendly countries in Iran's development plans," President Mohammed Khatami had said on the occasion.

He was referring to an agreement among India, Iran and Turkmenistan for exporting Indian goods by a road, rail and sea network through Iran and Central Asia to Russia and Europe.