The largest black tea producer in North Sumatra state plantation company PT. Perkebunan Nusantara IV exported US$1.987 million worth of black tea in the first four months of the year , up from US$1.243 million.

The increase in the export value was in line with the rise in volume, a section head at the provincial industry and trade office Fitra Kurnia said here on Tuesday.

In the first four months of 2013, black tea exports by the company totaled 663,916 kilograms , up to 1,193,740 kg in the same period this year.

Fitra said black tea is one of the provinces major export earners beside crude palm oil, rubber, coffee, spices , betel nuts and horticulture .

He said black tea is exported to a number of countries including Malaysia, Germany and Thailand.

"Hopefully PTPN IV could continue to maintain or expand its black tea production," he said.

Black tea has once disappeared from the ranks of major export commodities for North Sumatra as a result of shrinking price amid rising demand for palm oil, he said.

Many farmers stopped growing black tea in favor of other more profitable crops like oil palm in the province.

PTPN IV spokesman Syahrul Aman Siregar said the company will maintain its tea plantations and would improve the quality and the productivity of the plant.

In 2012, the company began to grow tea again cancelling plan to convert 1,600 hectares of its tea plantation into oil palm plantation.

"Indeed the price of black tea has not yet fully reached the normal level but the trend is encouraging," Syahrul said.