Japan's exports declined 3.3 percent in July from a year earlier as a strong yen and flagging overseas demand adversely affected trade, the Ministry of Finance said in a preliminary report Thursday.

The drop in exports compared to a median market forecast for a 2.6 percent decline and comes on the back of a 1.6 percent retreat booked in June.

The ministry's data showed that the value of exports totaled 5, 781.9 billion yen (75.6 billion U.S. dollars) in the recording period, marking the fifth successive month of decline.

Imports increased 9.9 percent on a customs-cleared basis to 5, 709.4 billion yen, less than the consensus forecast for a 10.9 percent expansion, while the trade balance for the recording period stood at a surplus of 72.5 billion yen (947 million U.S. dollars), the finance ministry said.

Due to power shortages in Japan after a number of nuclear power stations were taken offline for safety checks following the ongoing nuclear crisis sparked by a massive earthquake and tsunami crippling a nuclear power plant in the northeast of Japan in March, imports have surged on growing demand for liquified natural gas and crude oil from overseas.

Meanwhile, exports, although on a recovery path, were severely affected in the wake of the double March disasters, as key infrastructure were damaged and domestic and international supply chains disrupted due to parts shortages and an overall slowdown in factory output.