China's manufacturing downturn improved slightly in April as declines in new orders and output slowed, a preliminary survey showed on Wednesday, though factory activity showed an overall contraction for the fourth straight month.

The HSBC/Markit flash Purchasing Managers Index (PMI) for April rose to 48.3 from March's final reading of 48.0, still below the 50 line separating expansion from contraction.

The survey showed contractions in new orders and output moderated somewhat, though new export orders slipped back below the 50 line after a pickup in March, suggesting that the external environment remains difficult for Chinese firms.

The survey indicated a weak start to the new quarter, and came after figures last week showed that China's economy expanded 7.4 percent between January and March from a year earlier, its slowest pace in 18 months.

"Domestic demand showed mild improvement and deflationary pressures eased, but downside risks to growth are still evident as both new export orders and employment contracted," said Qu Hongbin, chief economist for China at HSBC, in a statement accompanying the PMI.

He added that he expected more government support measures in coming months.

Signs of a slowdown in the first quarter had been evident in a series of economic indicators, prompting the government to unveil a series of measures to promote growth, although it has ruled out major stimulus.

It has also said that its main focus will be on job creation, and that it did not matter if growth in 2014 came in a little below the official target of 7.5 percent.

The final Markit/HSBC manufacturing PMI for April is due on May 5.