The wreck of the Flying Phantom tug is to be raised from the Clyde today to allow accident investigators and police to examine the boat for clues as to why it capsized without warning, killing three of its four crew members.

Divers from the Maritime and Coastguard Agency (MCA) managed to lever the tug from its side into an upright position at the end of last week, and then spent the weekend attaching slings to the vessel in preparation for raising it out of the water.

It was hoped it could have been lifted completely from the river on Saturday or yesterday, but the divers' efforts were hampered by the tides and underwater currents, a spokesman for the MCA said yesterday.

Colin Mulvana, counterpollution and salvage officer for the MCA, said: "They encountered some more problems, largely due to the tides, so the weekend was spent continuing the preparation work; it's got to be done right before they attempt to lift it clear.

"They can only work at certain stages of the tide because of the currents, but hopefully we'll get it lifted on Monday morning."

Once the tug is raised by the lifting barge it will be taken to the George V Dock near the Braehead shopping mall, where experts from the Marine Accident Investigation Branch will examine it.

The Flying Phantom capsized suddenly near Clydebank on December 19 as it was involved in guiding a freighter to a dock on the Clyde.

The bodies of the skipper Stephen Humphreys, 33, from Greenock; Eric Blackley, 57, from Gourock; and Robert Cameron, 65, from Houston, were recovered later.

A fourth man, Brian Aitchison, 37, from Coldingham, was rescued from the water.

The investigation has yet to reveal why the boat sank so abruptly and without warning.