Anne Lewis, 51, swam fully clothed into the River Tyne at Tyne Riverside Country Park, Low Prudhoe after she saw an 18-year-old man who was trying to cross the river disappear beneath the surface.

Mrs Lewis, who had been walking her dog, went swimming into the water and managed to pull the man to the surface. However he began to panic and struggle, pushing Mrs Lewis under. The pair then trod water for several minutes until a friend of the man managed to get a rope to Mrs Lewis and drag them to safety.

Mrs Lewis and the man, who does not want to be identified, were both treated for shock but were otherwise unharmed. Mrs Lewis said: "I was walking my dog when it stopped for a paddle and I watched these two lads walking in the water before diving in. One of them just seemed to sink. At first I thought he was messing around but it soon became clear he wasn't.

"I went up to the bank and found a small buoy attached to a rope. I took this, waded in then swam out to where the man was. I dived under the surface and saw some bubbles. I got hold of the man and pulled him up but he panicked and clamped round my neck.

"Although he loosened his grip slightly he wouldn't let go and we basically trod water for several minutes. Fortunately the man's friend then came back with a rope and dragged us out."

Chief Inspector David Charlton, Northumberland Area Command, said: "This was an extremely brave act from a passer-by who risked her own life to save a man.

"It appears the man just lost consciousness but this once again highlights the dangers of swimming in open water. Although the air temperature may be warm, rivers can remain icy cold and the shock can lead even strong swimmers to get into difficulty.

"We would always warn people against swimming unsupervised in open water.

"If it wasn't for the quick thinking and brave actions of Mrs Lewis this could have turned into a tragedy."

Brian Hesler, Chief Fire Officer for Northumberland Fire and Rescue, added: "Mrs Lewis showed tremendous courage in rescuing this man, although I would stress that entering the water beyond your own depth should always be an absolute last resort when attempting a rescue.

"Using a throw line, or a long stick or pole to reach a person in difficulty should always be attempted first and rescuers should not endanger their own lives when attempting a rescue."

"In this case it appears that floating throw lines were present on the river bank and were put to good use in effecting the rescue.

"However, we would strongly advise people not to swim in open water, even if it looks safe."