The respective governments of China and Russia are seriously considering the idea of building a high-speed railway line between their two capital cities, according to reports.The Beijing Times said that the line, which would be over 7,000 kilometres but cutting the Trans-Siberian railway journey from six days to two, would cost in excess of $230bn (£142.9bn, €179.5bn) if it is to connect Moscow and Beijing via a high-speed railway line.If it were to be completed, it would be triple the length of the world's longest high-speed line which runs from Beijing to Guangzhou.Wang Meng-shu, a tunnel and railway expert at the Chinese Academy of Engineering, told the Beijing Times: "If the funds are raised smoothly... the line can be completed in five years at the quickest."Vladmir Putin and Premier Li Keqiang signed a memorandum of understanding when China's head of government travelled to Moscow earlier in the week, with the duo outlining their interested in building a high-speed link between Moscow and Kazan in the Tatarstan region, an area which holds vast amount of oil, China Central Television (CCTV) reported.