HANOI, Jan 13 (Reuters) - Vietnam reported a 19% growth in exports last year, as it saw its trade surplus with the United States, its largest export market, widening to an all time high, government data showed on Thursday showed. Vietnam"s total exports came in at $336.31 billion, while its imports rose 26.5% to $332.23 billion, resulting in a trade surplus of $4.08 billion, the Customs Department said in a statement. Exports in December increased 8.5% from November to $34.59 billion, while imports were up 3.1% to $31.62 billion, the department said. The data showed Vietnam"s trade surplus with the U.S. rose to $81 billion from $63 billion in the previous year, while its trade deficit with China widened to $54 billion from $35 billion. The U.S. is Vietnam"s largest export market for such products as garments, electronics and smartphones. Exports to the U.S. last year rose by a quarter to $96.3 billion. China is Vietnam"s largest trading partner, on which the Southeast Asian country relies heavily for materials and equipment for its labour-intensive manufacturing. Imports from China rose 30% to $110 billion.