HANOI, June 2 (Xinhua) -- Vietnam's economy has yet to bottom out despite a series of stimulus measures to bolster business confidence, Vietnam News reported on Friday.

Vietnam's exports in May extended the decline by a further 5.86 percent from a year ago, though at a slower pace than an annual contraction of 17.2 percent in April, according to the General Statistics Office (GSO).

The Southeast Asian country's exports have tumbled since last November, with a brief rebound in February, in the face of weaker demand abroad, adding urgency for support measures from the government, analysts said.

"There is no clear sign that Vietnam has bottomed out amid intensifying headwinds to growth," HSBC said in a report. "Indeed, sluggish external data remains the biggest downside risk to growth."

The data showed Vietnam's trade surplus with the U.S., its largest export market, narrowed 22 percent to 31.2 billion U.S. dollars in the first five months from a year ago.

Steep falls in exports included furniture, seafood, clothing, footwear and smartphones, which are the biggest foreign currency earners for the country.

Meanwhile, Vietnam's imports plummeted 18.4 percent in May, extending the downward trend seen over the last seven months.

Since imports contracted at a much faster pace than its exports, Vietnam's trade surplus widened to 2.24 billion dollars in May, twice the monthly average last year, data showed.

A widening trade surplus has partly kept the Vietnamese dong stable against the U.S. dollar so far this year, said HSBC.

"However, given Vietnam's import-intensive nature of the manufacturing sector, the extreme weakness in imports signals a sluggish rebound in future exports," HSBC noted.

About 94 percent of Vietnam's imports are raw materials and equipment for production in the first five months of the year, according to the latest data released by the GSO.

Vietnam's industrial output in May slightly rebounded by 2.2 percent from a year earlier, compared with an annual fall of 2.4 percent in April, said the GSO.

Despite such softer conditions, the S&P Global Vietnam Manufacturing Purchasing Managers' Index fell to 45.3 in May, well below the 50.0 threshold that separates expansion from contraction in manufacturing activity, marking a third straight month of declines.

One bright spot is the sector of retail sales and services, which grew 11.5 percent in May, partially offsetting external headwinds. But there is a clear divergence between big-ticket items, such as auto sales and tourism services, said HSBC.