Despite a heavy security presence, an ultra-Orthodox Jewish man on Thursday managed to stab six people during Jerusalem's annual gay march.

The man - 40-year-old Yishai Schlissel - was released three weeks ago after serving 10 years of a 12-year sentence for stabbing three participants at a 2005 gay parade in Jerusalem, according to police spokesperson Luba Samri.

"I saw an ultra-Orthodox youth stabbing everyone in his way," witness Shai Aviyor told Israel's Channel 2 television.

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

Schlissel was arrested by police immediately following the incident.

Israel's emergency services confirmed six young people were wounded in the attack, with two of them in critical condition.

'We will prosecute'

Israeli Prime Minister Benjamin Netanyahu wrote on Twitter that the perpetrator would be prosecuted.

"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," Netanyahu said.

Israeli President Reuven Rivlin also decried the attack, calling it a "hate crime."

"A terrible hate crime has happened here in Jerusalem, the capital of Israel - and people were stabbed who were celebrating their freedom to express their identity and world view," Rivlin said in statement.

Jerusalem's gay-pride parade was expected to draw thousands, though notably smaller than its Tel Aviv counterpart, which witnessed around 180,000 participants in June.

In 2006, Israeli politician and ultra-Orthodox Jew Baruch Marzel called for "holy war" against the gay parade, according to Israeli news site Ynet.

The parade was eventually cancelled, though several days of riots ensued in November as ultra-Orthodox protesters burned trash cans and clashed with police.

ls/kms (AP, AFP, Reuters, dpa)