Japan's exports rose at a slightly slower pace than expected in July, and shipment volumes extended their declines, data showed on Wednesday, adding to some doubts about the outlook for an economy that has only just started to pick up the recovery pace.

The outcome follows separate data last week that showed Japan's economy strongly rebounded in the second quarter on robust consumption, backing the case for the central bank to continue its monetary policy-tightening campaign.

Japanese exports rose 10.3% year-on-year in July, up for an eighth straight month, data from the Ministry of Finance showed, less than a median market forecast for an 11.4% increase.