The global aviation industry, already facing its biggest crisis in history, suffered further losses due to travel restrictions set up following the emergence of swine flu, the Association of Asia Pacific Airlines (AAPA) said Thursday.

Asia-Pacific airlines carried a total 10.1 million passengers in May, a huge dip of 1 million passengers from the month before and 14.8 per cent fewer than in May 2008.

The average passenger load factor dropped by six percentage points to 66.5 per cent, the lowest for the year, the association said in a statement.

Air cargo volumes continued to be depressed, registering a drop of 18.6 per cent year-on-year.

The dismal figures are expected to drop further in coming months following moves by governments to restrict air travel in the wake of swine-flu infections, the association's director-general Andrew Herdman warned.

"Anxieties over the spread of swine flu certainly aren't helping. Despite clear advice from the World Health Organization (WHO) against the imposition of border controls or travel restrictions, we have seen a number of governments, particularly here in the Asia-Pacific region, introducing such measures, in the mistaken belief that the spread of the virus can be contained," Herdman said in the statement.

"The unfortunate result is that the travelling public is being subjected to unnecessary inconvenience," he said.

"We urge governments to carefully review their actions, and to take full account of the wider economic and social impacts, before imposing further restrictions on the movement of people around the world."

Herdman said May's figures reinforce aviation analysts' predictions that a recovery in the industry was a long way to go.

"The operating environment remains extremely challenging," he said.

"The decline recorded in the month of May undermines any optimism that a recovery is already underway. We're still seeing a deterioration in market conditions," said Herdman.

AAPA's 17-member airlines recorded 141.5 million passengers last year, a 1.8-per-cent drop from the year before, and a 6.1-per-cent dip in air cargo.