Iran\'s state-run oil company is denying that China and Japan had sharply cut imports of Iranian crude, maintaining Tehran\'s assertions that economic sanctions imposed by the West were having little effect. Mohsen Qamsari, international affairs director of the National Iranian Oil Co, told the Mehr news agency that exports to China \"have not decreased at all\" and that \"all of the contracts between Japanese refineries and NIOC have been extended until the end of the year.\" He disputed official Chinese data showing imports of Iranian crude had fallen by more than half in March from a year earlier, and rejected reports that Japan may have cut its Iranian oil imports in April by 80 percent. China and Japan are the biggest customers for Iran\'s oil, alongside India and the European Union. While the EU is poised to fully implement an embargo on Iranian oil from July 1, China and India have been publicly resisting joining the Western sanctions. Japan has gone along with them sufficiently to satisfy its chief ally, the United States. The denials by NIOC about the Asian power-houses came as Iran is preparing for a new round of talks with the P5+1 (the five permanent UN Security Council members plus Germany) in Baghdad on May 23 that will focus on the sanctions and Tehran\'s nuclear programme. Iran\'s officials have been increasingly demanding that the sanctions targeting oil exports be lifted, while insisting that they were ineffective. Official data from China and Japan, though, showed that their purchases of Iranian oil had dropped. China\'s customs service figures showed March imports of Iranian oil had fallen by more than half to between 220,000 and 280,000 barrels per day, according to Dow Jones Newswires. But Qamsari said \"a 54 percent decrease in export of Iranian crude to China is not true,\" according to Mehr last week. \"On average 500,000 barrels of oil (per day) is exported to China in the current situation,\" he said. \"Oil exports to Chinese refineries in the current year have not decreased at all,\" he was quoted as saying. He added to the oil ministry\'s official SHANA news website: \"Not only the volume of Iran\'s exports to China has not dropped, it has increased compared to last year.\" On Wednesday, Qamsari told Mehr that exports were also normal with Japan, with all Japanese refinery contracts extended. \"On average about 220,000 barrels of Iranian crude are exported to Japan each day,\" he said. However, data from Japan\'s Ministry of Economy, Trade and Industry showed that Japan imported 36 percent less oil from Iran in March 2012 from a year earlier -- 1,334,012 kilolitres versus 2,096,400 kilolitres. During the same period, Japan upped oil imports from other nations, with shipments from Saudi Arabia rising 14 percent, the data showed. The Nikkei business daily has said Japan\'s Iranian oil imports could have fallen as much as 80 percent in April as EU sanctions make it tougher to get maritime insurance for the shipments. US President Barack Obama, in a Washington news conference on Monday with visiting Japanese Prime Minister Yoshihiko Noda, said: \"The regime in Tehran is now feeling the economic screws tighten, and one of the reasons is that countries like Japan made the decision to reduce oil imports from Iran.\" Iran relies on oil exports for around two-thirds of its foreign currency earnings. The Islamic republic is the second biggest exporter in OPEC, after Saudi Arabia. Last year, it exported some 2.6 million barrels per day of the 3.5 million bpd it pumped out of its huge reserves. The United States and the European Union have imposed their economic sanctions on Iran to pressure it over its disputed nuclear programme. The West and the UN\'s International Atomic Energy Agency suspect the programme includes a drive to develop the capability to make atomic weapons, despite Iran\'s repeated denials.