Kidnapped journalist Alan Johnston was released today after a 114-day ordeal.

The former Argus reporter who now works for the BBC, had been held in Gaza by a group calling itself the Army of Islam.

He said today he felt "the most unimaginable relief" after being freed in the early hours of this morning.

"It's just the most fantastic thing to be free," Mr Johnston, 45, told the BBC.

"It was an appalling experience, being kidnapped, occasionally quite terrifying and I didn't know when it was going to end.

"It became hard to imagine normal life. I dreamed several times of being free but always woke up in that room. It's incredibly good to be out."

Hamas had demanded Johnston's freedom since it seized control of Gaza last month.

Yesterday, Hamas gunmen took positions around the stronghold of the Army of Islam, stepping up the pressure to secure his release.

Hamas had said it knew where to find him but had not raided the hideout for fear he would be harmed.

But yesterday, members of Hamas' 6,000-strong militia moved on to rooftops of high-rise buildings and deployed gunmen in streets in the Gaza City neighbourhood inhabited by the Doghmush clan. The large, heavily armed family leads the Army of Islam.

Within hours, Alan Johnston, who worked at the Argus's Eastbourne office in the 80s, was free.

His parents Graham and Margaret Johnston said they were "absolutely overjoyed" that the "living nightmare" was over.

His father said he had a very brief telephone conversation with his son.

Mr Johnston Snr, speaking outside his home in Lochgoilhead, Argyll, said: "All he said was 'hello dad', and I said 'hello son. How are you? Are you all right?' "He said 'I am 100%' and then the phone was cut. That's all we've heard from him so far."

Prime Minister Gordon Brown said: "I welcome the good news of Alan Johnston's release. This will come as a great relief to his family and friends and all those who have worked to see him freed."

Mr Johnston was the only Western reporter permanently based in Gaza and had been working there for three years when he went missing on March 12.

After his release he told a press conference in Gaza: "It's hard to believe that I'm not going to wake up in a minute in that room again."

Mr Johnston said he had been able to listen to the radio after his first two weeks in captivity and heard messages of support.

"It gave me a psychological boost," he added.

"It was amazing to be lying in solitary confinement and hear people from Nigeria, Malaysia or friends from London, colleagues sending messages of support."

At the press conference, Mr Johnston said his kidnappers had initially told him they did not intend to kill or torture him but at 3am on the first night they covered his face with a hood and handcuffed him.

He added: "They were often rude and unpleasant. They did threaten my life a number of times. There was one 24 hour period when they seemed to get very angry and chained me up but that only lasted 24 hours.

"They were even occasionally friendly. One of the guards would let me go through and watch his television. But it was very grim.

"It was like being buried alive and removed from the world, in the hands of people who were dangerous and unpredictable."

He said there was no violence towards him until the last half hour of his captivity.

He said his kidnappers had become anxious when Hamas took over the region's security a few weeks ago.

Mr Johnston said he had managed to speak to his father.

Speaking of his family, who live in Scotland, he said: "It's so good, the thought that I will be with them soon."

It was not immediately clear when Mr Johnston would return to the UK.

The reporter told Sky News he would spend a "few days" regaining his strength and having a rest before returning to Scotland.

He said: "I think three years of Gaza as a correspondent followed by four months of kidnap in Gaza is probably more Gaza than most people need in their lives and I do not think I will be going back for some time."

His parents said they were still planning to travel to London to receive an award on his behalf tonight.

At about 5.45am today a Foreign Office spokesperson in London said: "I'm delighted to confirm that Alan Johnston is now in the care of officials from the British Consulate General in Jerusalem.

"Our top priority will be to ensure he is in good health and reunited with his family as soon as possible."

In a statement, the BBC said: "We are delighted and extremely relieved that our friend and colleague, Alan Johnston, has been released.

"This is wonderful news for his family, friends and colleagues - and everyone around the world who has shown their support for him over the past 114 days.

"We thank all of those who worked tirelessly - here and in the wider Middle East - to secure his freedom."

Former hostage Terry Waite advised Mr Johnston to "take time out" to come to terms with his ordeal.

Mr Waite, who spent 1,760 days in captivity in Lebanon until November 1991, said: "I heard the news in the middle of the night, I was just delighted."

He said that Mr Johnston would initially feel very excited but added: "The reaction sometimes sets in a little later later, he will do well just to take time out, to withdraw for a while."

More than 180,000 people signed an online petition calling for his immediate release which was organised by the BBC.