KABUL (Reuters) - Afghanistan's trade associations say they have halted trade with neighbouring Iran to protest an unexplained fuel blockade which has been choking the Afghan economy, the groups' leaders said on Tuesday. Tensions between the two nations have been rising over a de facto fuel export ban by Iran, which has stranded nearly 2,000 tankers at the border and pushed up fuel prices around Afghanistan. Only around 40 trucks are being allowed across each day. The President of the Afghan Chamber of Commerce, Qurban Haqjo, said thousands of independent traders have agreed to halt trade with Iran, which if implemented will suspend deals worth millions of dollars, and possibly damage Afghanistan's weak economy. "It is an independent decision by Afghan traders, and the ban starts from today (Tuesday)," Haqjo told a news conference in Kabul, adding that the government should encourage domestic production to fill the gap left by a dearth of Iranian imports. "This could badly hurt both Iran and Afghanistan but we had no other choice," Haqjo said. Also at the gathering were the heads of 21 traders associations, representing importers and exporters of everything from dried fruit to gemstones. Haqjo did not say how the plan would be monitored or comment on what level of losses traders who signed up might be able to absorb before being forced back into the market. Iran has not given any plausible explanations for the fuel clampdown, which has created a crisis in the country, Afghan Commerce Minister Anwar-ul-Haq Ahadi said. The Afghan Chamber of Commerce last week said it was told by Iranian officials the tankers were delayed because Tehran believed the fuel was destined for US and NATO forces, which are fighting a resilient insurgency. But NATO has repeatedly said it does not get any fuel supplies via Iran. Haqjo said estimates put Iran's annual imports to Afghanistan at over $800 million -- including cloth, food items, detergents and other accessories. Afghan exports are worth about $50 million annually, and are mostly rugs and gems. "I will scrap a five ton diesel deal with Iran," said Hataee, an Afghan trader who goes by one name. Lacklocked Afghanistan has little industry and is only now starting energy extraction, so it relies heavily on transit routes from neighbouring nations to bolster supplies of food, fuel and manufactured goods. More than 40 percent of Afghan oil comes through Iranian border, according to Afghan Commerce Minister Ahadi said. The severing of that supply link has caused prices to rise most dramatically in provinces near the Iranian border -- in some cases by up to 35 percent. Kabul has asked Kazakhstan to sell some 200,000 tons of fuel and private sector deals have been made with a Russian oil firm, as it rushes to ensure supplies don't dry up.