(Reuters) - South Korea's Samsung Electronics Co Ltd (005930.KS) has applied for a license to invest $3 billion in building a second smartphone factory in northern Vietnam, a government official said on Monday.

Samsung Electronics Vietnam plans to build the factory in Thai Nguyen province, where it opened a $2 billion smartphone plant in March, said a senior official at the province's Planning and Investment Department.

"We are working on the project," said the official, confirming an earlier report by Dau Tu, a newspaper controlled by Vietnam's Planning and Investment Ministry. "There are still a few things to fix."

The official was not authorized to speak to media on the matter and so declined to be identified by name. Officials at Samsung Electronics in Vietnam and South Korea declined to comment.

Samsung has been increasing production in Vietnam to reduce costs and better compete with the low-priced smartphones of Chinese rivals in particular.

The company's latest move would bring its total investment pledges in Vietnam this year to around $11 billion, according to Dau Tu newspaper, whose controlling ministry oversees foreign investment.

Mobile phones and accessories became Vietnam's biggest cash earner last year, taking over textiles. In January-October this year, export revenue reached $19.2 billion, or around 15 percent of the country's total.

Samsung's first smartphone plant in Vietnam, built with an investment of $2 billion, generated $1.9 billion in export revenue in its first four months of operation, according to the Thai Nguyen provincial government.

The government, in a statement earlier this month, said the company's total revenue is expected to jump more than 67 percent to $13.4 billion next year from $8 billion projected for 2014.

(Reporting by Ho Binh Minh)