TBILISI (AFP) - The European Union on Monday condemned the violent disruption of a gay rights rally in Georgia by thousands of ultra-conservative Orthodox church supporters led by priests.

The EU office here said in a statement it "was dismayed by the scenes of brutal intolerance and violence committed by some demonstrators on May 17 with a declared desire to prevent other demonstrators from expressing themselves peacefully".

Scores of gay rights activists were forced last Friday to flee a rally in the capital Tbilisi organised to mark International Day against Homophobia after thousands of Orthodox supporters headed by black-robed priests broke through police cordons.

Activists had to board buses provided by the police to escape the mob, which charged after them across Tbilisi's main square hurling stones, breaking windows and threatening to kill them.

Prime Minister Bidzina Ivanishvili, who had previously pledged that the police would protect the rights rally, said that the violence would not be tolerated and promised that "perpetrators of such acts will be dealt with according to the law".

A police spokesman told Agence France-Presse on Monday that investigations were underway, but refused to say if anyone had been arrested over the violence, in which the local media reported around 20 people were injured.

A coalition of local rights groups that observed the incident lashed out at the police for their "inadequate and ineffective" security provisions, and said some officers had appeared to be sympathising with the anti-gay protesters.

The authorities should "investigate and bring to account all those who prevented the citizens from holding the planned rally", said the statement from rights groups.

Homosexuality is still highly stigmatised in Georgia, a socially conservative country in the Caucasus where the immensely influential Orthodox Church has previously clashed with Western-leaning governments over social issues.

In the run-up to the planned rally, Patriarch Ilia II, the head of Georgia's Orthodox Church, called on the authorities to ban the demonstration, saying homosexuality was an "anomaly and illness".