UK broadcaster Channel 5 has parted company with its chief executive David Elstein, in a shock move announced to staff on Friday afternoon.

Channel 5's director of programmes Dawn Airey is to take over from Elstein, who leaves immediately after four years with no other job to go to.

In a statement, Channel 5 said Elstein was exercising his contractual share options. Elstein commented: "My contract was geared to optioning my benefits as soon as I had completed four years in charge. I left it to the shareholders to choose the actual moment of exercise and they have acted at a time when the channel needs to take a deep breath, galvanise its forces and move on to stage two of its life."

The move came as a complete surprise to staff who were told at a meeting on Friday. One commented: "It's come as a complete shock, but we're also very excited about what it means for the future."

UK media reports have already speculated that Elstein was sacrificed to make way for Airey, who is known to have received a number of high-profile job offers in recent years from rival broadcasters.

Airey, 39, joined Channel 5 in February 1996. She will continue in her current role as director of programmes for the time being.