Thousands of frustrated passengers began flying out of Asia's airports for Europe on Wednesday, almost a week after volcanic ash closed European skies.

From Sydney to Seoul, Islamabad to Beijing, people rushed to airports as authorities lifted a six-day lockdown that has wrought untold economic losses and frayed the nerves of trapped travellers.

At Seoul's Incheon Airport, the VIP and staff lounges were beginning to empty after being turned into dorms for over 200 transit passengers stuck there for up to five days.

"We've provided them with mattresses and pillows, bottled water and three meals a day. It's all for free," Yoon Han-Young, the airport's customer service team leader, told AFP.

At Sydney airport, tourists, students and business people waited five-deep in a queue stretching around 200 yards (180 metres) through the departure lounge, many days late for school or work.

Everyone from young babies to a man in his nineties waited patiently for about two hours after being summoned to the airport by text message or a phone call from British Airways.

"I think everyone's at the end of their tether," said TV producer Jane Gershfield, clutching her ticket and passport.

"People don't realise how difficult it is. People just think, okay, you've got a few days in Sydney. But you've got no idea how you're going to get back, that's the difficult thing.

"You're absolutely in limbo."

Hong Kong's Cathay Pacific announced a raft of flights to Europe and most mainland Chinese airlines resumed their European services.

Jason Woodcock, a member of the British Army who has been stranded in Hong Kong, said he was told by Cathay staff at his hotel that he could fly back to London on Wednesday.

"I rushed to the airport with my girlfriend and queued for an hour-and-a-half -- only to learn that there would be no flight for us until May 5," he said.

"Now that the gate is open, there is a mad rush to get through the system. There is a lack of control and communication between airline staff."

Ethan Wilson, 19, said he and his three friends had to camp out at the airport after being told by British Airways that they had to wait till May 9 to fly back to London.

"We have been travelling in Southeast Asia over the last few weeks. We have spent all our money. The airline has offered us nothing but a hotline which we cannot get through," he said.

In Islamabad, Pakistan International Airlines began making plans for around 18,000 passengers, about half stuck in Pakistan and half overseas, trying to get home. It will be a slow process.

"We will need two to three weeks to dispatch all the passengers who are stranded," airline spokesman Sultan Hasan warned.

In Manila, Philippine Airlines said it was hoping European authorities would lift a safety ban on it flying through their airspace so it could help bring Filipinos home.

Singapore Airlines put on eight planes in and out of Europe from the city state's Changi Airport, giving priority to the elderly, those with special needs and those with infants or young children.

But airlines expect it will take weeks to clear the backlog, after ash from an Icelandic volcano hovered over Europe, threatening to clog jet engines.

The Association of Asia Pacific Airlines said the region's carriers had bled about 40 million dollars a day, while the International Air Transport Association put airlines' global losses at about 270 million dollars a day.

"If you really go all the way through to the taxi drivers in Thailand, the impact goes into billions (of dollars), it's just a matter of how far down the chain you want to go," said Peter Harbison, executive chairman of the Centre for Asia Pacific Aviation consultancy.

Back at Sydney airport, the industry's lifeblood -- its passengers -- were counting their own costs, from extra accommodation to missed meetings and clothes left in hotel laundries in the hurry to get to the airport.

Northern Ireland's Anne and Craig Simpson were among the lucky ones, as they had extra time to spend with their daughter Victoria, who lives in Sydney, and their eight-week-old granddaughter, Abigail.

"There's always a silver lining," Victoria said.