A Liberal Democrat MP has been injured and a colleague was stabbed to death after they were apparently attacked with a sword, police have said.

Cheltenham MP Nigel Jones is being treated overnight at Cheltenham General Hospital for cuts to his hands after the attack in his constituency office in St George's Street at 1630 GMT.

Police said they arrested a 49-year-old man from Cheltenham in connection with the incident, 10 minutes after they received the emergency call, and have launched a murder inquiry. A weapon has been recovered.

The deceased man has not been named.

Mr Jones, a father of three, was said to be "fine" in hospital after receiving emergency treatment.

He was sitting up and chatting with his family, Cheltenham Mayor Dave Banyard said following a visit to the hospital.

The weapon used in the attack is believed to be a sword but this has not yet been confirmed by police.

A spokesman for Cheltenham police, Inspector Martin Surl, said: "I can't tell you what the motive here was at this stage. I can tell you that a man has been arrested for murder.

"We have launched a very comprehensive investigation to get to the bottom of why this tragedy has actually happened.

"At the moment we are working hard with the family of the deceased person to offer them support, and to make sure they are kept up to date as to what the progress is."

Liberal Democrat leader Charles Kennedy summed up his party's shock at the incident.

He said in a statement: "I am shocked and horrified by this news. Members of Parliament make themselves available to their constituents.

"It is tragic that an MP and his staff, carrying out their duties, should be subjected to an appalling attack of this nature."

Eye witnesses told the BBC that they saw a 6ft man brandishing what looked like a Samurai sword going into Mr Jones's surgery.

One described how the man appeared to go "crazy".

Mouth-to-mouth

Neighbour Graham Norton, 33, of St George's Street, told how his friend David Copson nursed the dying man in his arms.

Mr Copson tried to give the stabbed man the kiss of life and held him as he bled to death from a wound in his side.

Mr Norton said: "When I came home my friend was white as a sheet with shock. The man died in his arms.

"He tried his best to save this man and gave him mouth-to-mouth but he said there was a hole in the man's stomach."

No knowledge of threats

Cheltenham borough councillor Brian Cassin said the MP and his assistants had been preparing for their Friday night surgery, which is held between 1730 GMT and 1900 GMT, when they were attacked.

In a statement, Home Secretary Jack Straw said: "I share the deep sense of shock that everyone will feel at the death of Nigel Jones's assistant following this horrific attack.

A spokeswoman at the Liberal Democrat's head office in London said: "One of my colleagues has spoken to Mr Jones and he is fine. He suffered lacerations to his hands."

"We don't know if he will be kept in overnight."

Liberal Democrat spokesman David Walter said he had no information that Mr Jones had been the subject of any threats in the past.

He said the party's condolences went out to the family of the dead man.

Mr Jones won the Cheltenham seat in 1992. At the last election, he had a majority of 6,645.

He moved into full-time politics following a career as a computer programmer and systems analyst.