Russia and Kazakhstan launched their customs union today in the first step towards creating of an ex-Soviet common market for 160 million people, brushing aside criticism from the West over protectionism, Reuters reported. The third ally Belarus, which chose to drop out of the Union's launch due to the energy trade disputes with Moscow, was still welcome to join, Russian Prime Minister Vladimir Putin told a government session. "I believe we need to start work in a trilateral format from the beginning, with active participation of our Belarussian partners," Putin said. "The doors for such integration are open ... Integration with neighbours is the historical choice for Russia." Russia and Kazakhstan will from July 1 use a single customs code, although a transition period exists for a range of goods, meaning that the two nations have not completely unified their tariff legislation. Putin took markets by surprise last year when he said that Russia was dropping its long-standing bid to join the World Trade Organisation (WTO) in favour of the customs union, saying the union promised immediate trade benefits for its members. Russia has this year revived the WTO bid but the prospects of membership either unilaterally or as part of the union look unclear.