The tempting taboo of Iran's oil and gas riches has moved a step nearer for Western oil companies, lining up to woo Tehran if sanctions finally succumb to a diplomatic thaw. US oil firms - barred by Washington from Iran for nearly two decades - planned to meet Oil Minister Bijan Zanganeh last week at the United Nations, encouraged by the new tone in Tehran, industry sources said. Related stories: Biden: Nuclear Iran dangerous to Israel Iranian FM: Israel can't kill all our scientists Iran FM accuses Netanyahu of 'lies' "We're willing to talk: Iran's got tremendous potential," said a senior executive from a major U.S. oil company who requested anonymity while preparing for exploratory talks. "Once sanctions are removed, we'd definitely be interested in investing, but the contract terms have got to be attractive." US companies Conoco, Chevron, Exxon Mobil and Anadarko have all shown varying degrees of interest in the Islamic Republic ever since Tehran nationalised its energy sector in 1979. Zanganeh served as oil minister under Iran's reformist government from 1997-2005. He intended to travel with President Hassan Rouhani to New York, but called off the trip at the last minute, the sources said. Iran's largest oil field (Photo: MCT) Executives from US and European companies will be seeking new opportunities to meet with Iranian oil officials on neutral ground, industry sources said. US and European companies contacted by Reuters declined comment for this story. "There is no embargo on talks," said a senior European oil executive, who requested anonymity. The apparent thaw in relations between Iran and the US may also lead, according to Iranian media, to the end of the slogan most-identified with Tehran – "Death to America" – chanted by clenched-fist worshippers every Friday in the Islamic Republic. According to the BBC, one prominent preacher insists the slogan isn't Holy writ. "It's not like the Koran commands us to chant 'Death to America' for ever," Mohammad Taqi Rahbar told Qanun newspaper. "We used to shout 'Death to the Soviet Union' too, but, just as we've sorted things out with the Russians, so we can sort things out with the US," he added. But meanwhile, AP news agency reported this Friday that the master-of-ceremonies led the crowd into the chant at least twice during prayers. It was then repeated several times by a group of worshippers who rallied after the ceremony, burning the American and Israeli flags, as they do almost every week. Iran-watchers are now waiting to see what happens on 4 November, the anniversary of the storming of the US embassy in Tehran, when the slogan usually gets its most prominent annual airing. However, Ayatollah Kazem Sedighi, a cleric who led the prayers in the Iranian capital, tried to strike middle ground, saying America and Iran should "join hands" in a struggle to overcome sanctions that have crippled Iran's economy. Sedighi also says Iran will not pull back from its "peaceful nuclear rights." Follow Ynetnews on Facebook and Twitter Receive Ynetnews updates directly to your desktop