STANSTED, England (AP) _ Eighty-five men, women and children walked down the tail staircase of a hijacked Afghan plane early Thursday, raising hopes that a hostage drama could be nearing an end.

The largest release of hostages so far came about 3:30 a.m., nearly four days after the plane was hijacked. But police said dozens of hostages and their captors were still aboard the Boeing 727, parked at Stansted airport near London.

The heavily armed hijackers let women and children leave the aircraft first, said Joe Edwards, Essex County police assistant chief constable. The hostages will be taken to a safe location and undergo medical evaluations, he said.

``All those who left are indeed hostages,'' Edwards said. ``There are still people on board, negotiations continue,'' he said. ``The negotiations are also at a fairly critical stage.''

Before the release, officials said 151 people, including 21 children, were believed on board the aircraft, which was hijacked early Sunday on a domestic flight leaving Kabul, Afghanistan's capital. It then began a meandering journey across the former Soviet Union, stopping in Uzbekistan, Kazakstan and Russia.

As the surprise release got under way, police vehicles parked nearby and bright lights shined up the staircase toward a steady stream of people walking leaving the Ariana airlines jetliner.

Moments before that, two people seen leaving the aircraft were hijackers bound for a meeting with negotiators on the tarmac outside the plane, said Edwardsd.

``We have worked hard throughout the day to build on the trust,'' he said. ``We have negotiated a face-to-face encounter between us and two hostage takers.''

Police had expressed hope on Wednesday that a resolution was close.

Among the captives were 39 members of one family who were traveling to a wedding in the northern Afghan city of Mazar-e-Sharif _ including the would-be bride, said Mohammed Daoud Sharisi, who sells tickets at the Ariana office in Kabul.

Speculation also mounted in the British media that the plane was seized as part of an elaborate bid for political asylum _ and that some of the hostages were in on it.

``HI-HOAX? Hijackers and hostages may be asylum seekers,'' the tabloid Mirror blared on its front page. The Daily Star lamented ``Oh no! They ALL want to stay (and we'll have to pay).''

Fueling the asylum speculation was the arrival Tuesday of an observer from the office of the U.N. High Commissioner for Refugees. The observer would be providing expertise but would not be joining the negotiating team, said Edwards. The commission's London office identified the observer as Hope Hanlan.

Responding to questions about the validity of the asylum theory, Edwards said: ``Why are they still in there? We've been asking them to come out since Monday.''

Earlier Wednesday, the hijackers ejected a flight attendant, who was seen being sent forcibly down a set of stairs at the rear of the plane. His departure came four hours after four crew members _ the captain, second captain, first officer and flight engineer _ escaped by using a rope to lower themselves from the cockpit and jumping onto the tarmac.

Four men, presumed to be hijackers, appeared briefly on the ground at the rear of the plane Wednesday morning to collect fresh supplies. That evening, two men descended the jet's rear steps and collected an evening meal _ a result of the continuing negotiations. They appeared to carry out an inspection of the aircraft.

Negotiators had insisted that the armed men had made no formal demands, political or otherwise. The men, believed to be Afghans, were armed with grenades, pistols and daggers.

In Kabul, an Ariana employee said Wednesday that several airline officials responsible for security checks on the hijacked flight had been arrested. An Interior Ministry official, speaking on condition of anonymity, said several employees were questioned but allowed to go back to work.