An Orthodox Jewish assailant stabbed and wounded six participants in the annual Gay Pride march in Jerusalem on Thursday, police said.

Yishai Shlissel spent 10 years in jail for a similar attack a decade ago when three marchers were wounded.

Prime Minister Benjamin Netanyahu condemned 'as a most serious incident' what was the worst attack in years on the event in Jerusalem, a city where the religious population is more prominent than in other parts of Israel.

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Yishai Shlissel brandishing a knife runs towards one of the people taking part in Jerusalem's Gay Pride event

Eyewitnesses screamed after the Shlissel jumped from the crowd and tried to stab several of the revellers

It later emerged that Shlissel had spent 10 years in prison for an almost identical attack

Police wrestled Shlissel to the ground and arrested him following his rampage earlier this afternoon

Police recovered a six-inch long blade after they arrested Shlissel at today's Jerusalem Gay Pride march

Marchers numbering about 5,000 and waving banners were heading down an avenue when an ultra-Orthodox man jumped into the crowd and plunged a knife into some of them, witnesses said.

Police arrested Shlissel at the scene and were questioning him, police spokesman Assi Aharoni said.

It is understood that Schlissel was only released from prison three weeks ago following his 2005 attack which injured three people.

Police and medics said the assailant had wounded six people. Two were taken to hospital in serious condition.

Jerusalem police confirmed the suspect had recently been released from prison after carrying out an almost-identical knife attack on the city's gay pride festival in 2005.

'I saw an ultra-Orthodox youth stabbing everyone in his way,' said Shai Aviyor, a witness interviewed on Israel's Channel 2 television.

'We heard people screaming, everyone ran for cover, and there were bloodied people on the ground,' Aviyor said.

A photographer captured this image Yishai Shlissel moments before he stabbed six people earlier today

Police led Shlissel, second right, away from the scene for questioning following today's incident

Some six people were wounded during the rampage with two of them reportedly in a critical condition

The march, which attracts thousands of participants, has long been a focus of tension between Israel's predominantly secular majority and the ultra-Orthodox Jewish minority, who object to public displays of homosexuality.

While the event takes place annually in the more gay friendly business hub of Tel Aviv without incident, in Jerusalem, where the religious population is more prominent, violence has erupted in the past.

The march is held in the largely Jewish side of the divided city. Palestinians predominate in occupied East Jerusalem.

A police officer handcuffs Shlissel as he is pinned to the ground after the attack

Witnesses said that Shlissel, right, pulled a knife and started stabbing participants on today's gay pride march

Medics and ambulance workers raced to the scene to treat some of the critically wounded victims

Organisers deliberately routed the march away from ultra-Orthodox areas of Jerusalem to avoid offence

Oded Fried, the head of a leading gay rights group, said the attack would not deter the movement.

'Our struggle for equality only intensifies in the face of such events,' he said.

Netanyahu said in a statement: 'This is a most serious incident. We will prosecute those responsible to the full extent of the law. Freedom of individual choice is a basic value in Israel.'

After police arrested Shlissel, participants carried on with the march through streets decked with rainbow flags to a park where a party was planned for the evening.

Hundreds of police are deployed to prevent violence breaking out in the highly conservative city during the annual march.

In past years, ultra-Orthodox protesters have gathered in their Mea Shearim bastion to denounce what they consider the 'abomination' of homosexuality.

Shocked revellers consoled each other after six people were wounded during Jerusalem's gay pride festival

Fellow marchers helped those who had been stabbed by applying direct pressure to their wounds

Organisers of Thursday's march avoided ultra-Orthodox sectors to try to avoid incidents.

Israel's gay community was plunged into grief in 2009 when a gunman attacked a centre for young gays in Tel Aviv killing two people and wounding some 15 others.

That assailant has never been apprehended.

Israel is widely seen as having liberal gay rights policies, despite the ultra-Orthodox hostility towards homosexuals, particularly men.

The Jewish state repealed a ban on consensual same-sex sexual acts in 1988.

Eyewitnesses claimed that Shlissel waited inside a supermarket until the marchers reached him when he struck.

Eyewitnesses said that Shlissel waited in a supermarket for the march to approach before launching his attack

Two of the victims were described as being in a critical condition as they were rushed to hospital for treatment

Israeli political leaders condemned the attack which saw six people hospitalised with stab wounds

Jerusalem police spokesman Asi Ahroni said there was a 'massive presence' of police securing the parade but 'unfortunately the man managed to pull out a knife and attack'.

A medic that treated the wounded at the scene, Hanoch Zelinger, said one woman was stabbed in the back, chest and neck, and was lying unconscious on the ground.

Shaarei Tzedek hospital said it was treating a man with stab wounds who was in serious condition and a woman in critical condition, both in their 20s.

The parade continued after the wounded were taken for treatment, but in a more somber atmosphere. Media reported that thousands of Jerusalem residents who had not participated in the parade joined in after the attack in solidarity.

Benny Zupick, 21 said after the attack: 'I do think that homophobia is rooted in the city, but that's the point of the parade. We are trying to change that. And hopefully we will change that. It takes one man to create a scene like this. Hopefully he's a minority.'

A majority of Jerusalem's residents are either observant Jews or Muslim or Christian Palestinians, conservative communities that oppose homosexuality. Previous parades have drawn opposition.