DAR ES SALAAM (Reuters) - Tanzania's economic growth slowed in the second quarter compared with the same period a year ago, hit by slowdowns in the manufacturing, construction, transport and communications sectors, data showed on Saturday.

The manufacturing sector, an important source of foreign exchange, slowed to 6.9 percent growth, from 10.1 percent a year before. Construction expanded by 13.2 percent versus 37.5 percent growth previously, while transport expanded 8.8 percent, down from 9.7 percent a year before.

The communication sector recorded growth of 17.4 percent, compared with 18.4 percent in the second quarter of 2014.tan

Industries that recorded faster growth include agriculture which expanded 4.2 percent in the second quarter of this year versus 3.8 percent previously. Mining and quarrying activity grew by 8.3 percent, compared with 6.4 percent a year before, due to increased gold and diamond production.

Gold output rose to 10.682 tonnes in the quarter from 9.917 tonnes a year before, while diamond output increased to 52,928 carats, from 50,277 carats.

Tanzania is Africa's fourth-biggest gold producer after South Africa, Ghana and Mali and gold exports are another important source of foreign exchange.

Tanzania has forecast that the economy will grow by 7.4 percent this year from an estimated 7.2 percent in 2014, due to expected strong performance of agriculture, construction and manufacturing sectors.