A LOCK along the River Thames has been closed after a boat sank below the water's surface yesterday.

The boat was submerged in the river at Clifton Lock, between Clifton Hampden and Long Wittenham.

A witness said it was carrying gravel and one man was on board, but it is understood he escaped unharmed before it went down. 

Several river users on social media have criticised the Environment Agency, and said there was no lock keeper on duty at the time.

Images posted on Facebook by 'Imbote Boats' show the blue vessel poking out from the water, and the accompanying text claimed there was no lock keeper on duty at the time.

Replying to a comment, the post added: "The sluices [lock gates] opened going up, water pulled [the boat] forward and it got trapped in the gate, the low loader carrying gravel.

"It went down in under a minute, there was nothing we could do except close the sluices and open the tail sluices."

One commenter said: "This is a serious mishap on behalf of the EA - had the lock been manned, this would not have happened.

"This was a lucky escape for the guy on the boat and quite frankly the EA really should be manning the locks.

"This time no one was hurt."

Debbie Curtis of Imbote Boats, which is currently creating a television documentary about the River Thames under Aqua Dog Productions, watched the scene unfold.

She said: "It was very dangerous and a lock keeper, without doubt, would have prevented this happening.

"The biggest problem at the moment is the lack of lock keepers in general along the Thames.

"They are getting fewer and further between, and locks left unattended ae putting the public at risk."

She said there is a resident lock keeper at Clifton Lock and he was 'completely blameless in this scenario' as he was on leave, but she said the EA should have brought in a relief lock keeper.

A notice on the Environment Agency's website said: "Clifton Lock will be closed to all boats due to the sinking of a vessel in the chamber.

"No public mooring will be allowed in the lock laybys, up and downstream of Clifton Lock.

"The main navigation channel will remain open throughout the incident up and downstream of the lock.

"There is no passage through Clifton Lock at this time.

"This closure is for the safety of river users, pollution prevention and to recover the sunken craft.

"We apologise for any inconvenience it may cause."

The notice said the closure would be in place from midday yesterday until midday today.

But an Environment Agency spokesperson told the Oxford Mail: "Clifton Lock will remain closed today until further notice – a revised harbour master notice will be issued later today."

It has not yet commented on criticism about the lack of a lock keeper.