HONG KONG - Hong Kong student leader Joshua Wong, the teenage face of the city's pro-democracy protests, was assaulted in the street with his girlfriend in an attack he said yesterday sent a "chill to my heart".

The motive for the attack is not known, but previous attacks against prominent media figures have raised concerns that tensions from Hong Kong's deep political divisions could turn violent.

Mr Wong, 18, was leaving a cinema near Mong Kok - the scene of some of the most bitter clashes during last year's street rallies - with his girlfriend late on Sunday when the assault occurred.

The male attacker punched Mr Wong in the face and, when he and his girlfriend gave chase, both were assaulted, he said on his Facebook page.

"Being attacked on the way home after going on a date, and even attacking my girlfriend, it's shameful," he said.

Police said yesterday they had yet to make an arrest, confirming that Mr Wong had "suddenly been attacked" by a suspect in his 20s and had suffered injuries to his eyes and nose.

"The suspect tried to flee but the two victims followed, and when the female tried to take pictures of the suspect, he then attacked the male and female victims," a police spokesman said.

Last year's mass protests were sparked after Beijing insisted that candidates for Hong Kong's next leader must be vetted by a loyalist committee, a decision that campaigners, including Mr Wong, derided as "fake democracy".

The electoral proposals were voted down earlier this month after a protracted debate that divided the city.

"(The assault) implies activists are facing the danger of attacks in their daily lives, not only during protests. This is what sends a chill to my heart," Mr Wong wrote in an emotional Facebook post.

Other leading anti-establishment figures targeted in the past include media tycoon Jimmy Lai, whose office and home were firebombed in January.

Separately, scuffles broke out between what police described as rival protest groups in Mong Kok on Sunday night. Five people were arrested after police used pepper spray to separate the groups, the South China Morning Post reported.

The newspaper said the conflict broke out between a pro-Beijing group and "anti-mainland demonstrators".

Political analyst Sonny Lo said that Hong Kong was becoming increasingly polarised with small groups becoming "highly politicised by an increasingly radicalised environment".

AGENCE FRANCE-PRESSE