ATHENS: Police in Athens are holding two Greek men as suspects over the fatal stabbing early Thursday of a Pakistani immigrant worker near the city center, and are investigating whether the attack was racially motivated.

A police statement said the 26-year-old Pakistani man was attacked on his bicycle by two men on a motorbike before dawn, in the Petralona district of Athens.

The two suspects, both in their twenties, were arrested shortly afterward in the city center, and police said they were carrying switchblades.

Police say the motive of the killing was not immediately clear.

Greece, in the midst of its worst financial crisis in decades, is the main entry point to the European Union for thousands of illegal immigrants, most of whom end up stranded there in dire conditions.

Immigrants from Asia and Africa have repeatedly been targeted in violent night-time attacks by thugs, amid a surge in anti-immigration rhetoric that has brought a fringe ultra-right party to Parliament. Its political opponents, including all three parties in Greece's governing coalition, have accused the Golden Dawn party of holding a neo-Nazi agenda and inciting and participating in racially-motivated violence - charges the party denies.

The main opposition Radical Left Coalition party issued a statement blaming the fatal stabbing on right wing extremists.

"The savage racist murder of an immigrant by far-right criminals once again brings to the public attention, in a tragic way, the issue of crude racist violence," a party statement said.

It claimed that "fascist criminal gangs are patrolling the streets of Athens unhindered, murdering unprotected people."

Anti-racism activist Petros Constantinou said the "neo-Nazi" killing fitted in a pattern of racist violence.

"There have been many attacks after nightfall, involving people on motorcycles who target immigrants who are either on foot, on bicycles or on scooters," he said.

Human rights groups have recorded more than 70 racist attacks in Athens between January and September last year. Most were carried out after dark in public areas and involved more than one aggressor.

In a report last month, UN Special Rapporteur on the human rights of migrants Francois Crepeau voiced deep concern at the "widespread xenophobic violence and attacks" against migrants in Greece. Crepeau accused law enforcement agencies of responding inadequately, and said many attacks go unreported as illegal migrants fear they will be detained and deported if they contact the police.

Anti-racism groups will hold a march to the spot of the killing later Thursday. A major anti-racist protest has been planned for central Athens on Saturday.