EU and Russian leaders are due to open a two-day summit, marred by Moscow's recent ban on EU vegetable imports following a deadly E. coli outbreak. Brussels has condemned last week's measure as disproportionate, but Russia says it wants to know the source of the outbreak before lifting the ban. The outbreak has so far left at least 26 dead, most of them in Germany. At the talks in Nizhny Novgorod, the EU and Russia will also discuss gas pipeline projects and visa-free travel. Meanwhile, the EU has increased to 210 million euros its offer of compensation to farmers who have lost income due to E. coli crisis. Ahead of the biannual summit in the city on the Volga river, Dutch Agriculture Minister Hans Bleker downplayed hopes for a quick resolution of the rift between the two sides over last Thursday's ban on vegetables. He added that he had no expectations that there will be an end to the export ban within a couple of days. Russia imports about one-fifth of its vegetables from the EU, which makes it the bloc's largest market for the produce.