Cambodia imported 453,000 tons of petroleum in the first three months of 2014, up 10 percent from 412,190 tons over the same period last year, the data of the Ministry of Commerce showed Tuesday. During the January-March period this year, the country spent 442 million U.S. dollars in purchasing oil, up 11 percent from 397 million U.S. dollars over the same period last year, the data said. The Southeast Asian nation entirely imports petroleum from Vietnam, Singapore and Thailand as its seabed's oil and gas have not been exploited. A liter of premium gasoline costs 1.35 U.S. dollars in Phnom Penh on Tuesday. The country has planned to build a 5-million-ton oil refinery under a joint venture between Cambodian and Chinese companies. Cambodian Prime Minister Hun Sen said last October that he would push for the construction of the oil refinery by 2018. The project, estimated to cost 1.67 billion U.S. dollars, will be built on the 80-hectare area within the boundary of Preah Sihanouk and Kampot provinces.