Hopes for a recovery of Japan's battered economy took a knock on Friday after new figures showed industrial activity fell in April.

The all-industries index published by the economy and trade ministry showed activity slipping 1.3% in April from March, which had registered a 1.2% rise.

The sector had seen growth in the first three months of the year - but April's figures are now likely to reinforce the impression that this was just a flash in the pan.

"I see a danger of prolonged economic weakness," said Takeo Hiranuma, economy and trade minister.

"Conditions in our economy are still severe, with the corporate and employment environment still having downside risks."

Any bright spots?

The tertiary sector index - looking at the service industry - was down 1.5% in April.

The construction sector saw activity slip 5.1% in April, following a smaller fall the month before.

"Overall, my impression is that there is no sector that is particularly strong," said Kazuaki Hasegawa, the ministry's director of current statistics.

"It's hard to say which sector might be able to pull the economy forward."

The ministry's survey did show some encouraging signs.

The industrial production sector managed to stay in the black, registering a 0.2% rise after March's 0.8% rise.

Carmaker Honda, for example, has said its domestic vehicle output for May is 15.9% higher than a year ago - reflecting Japan's strong export performance.

Exports on the rise

The news comes just a day after economic data showed an increase in Japanese exports.

The trade surplus almost doubled in May from April.

These figures can be seen as reflecting the recovery elsewhere in the world, hence demand for Japanese exports.

This demand was also boosted by a weak yen, making Japanese goods cheaper.

The yen has however since strengthened against a weaker dollar.