Hong Kong student leader Joshua Wong, the teenage face of the city's recent pro-democracy protests, has been assaulted in the street, along with his girlfriend, in an attack that he said sent a "chill to my heart".
"Being attacked on the way home after going on a date, and even attacking my girlfriend, it's shameful," Wong wrote on Monday on his Facebook page.
Wong, 18, was leaving a cinema near Mong Kok - the scene of some of the most bitter clashes during the territory's street rallies - with his girlfriend late on Sunday when the assault occurred.
The male attacker punched Wong in the face, and when he and his girlfriend gave chase, both were assaulted, Wong said.
A photo published by the Reuters news agency on Monday showed Wong with a wound in the left side of his nose, and swelling below his left eye.
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The motivation for the assault 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.
Police said on Monday that they had yet to make an arrest, confirming that Wong had "suddenly been attacked" by a suspect in his 20s and had sustained injuries to his eyes and nose.
The incident comes just days before a major pro-democracy march on Wednesday, when thousands are expected to take to the streets.
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 campaigners, including Wong, derided as "fake democracy".
The electoral proposals were voted down earlier this month after a protracted debate that divided the city.
'Bumpy road of democracy'
"[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," Wong wrote.
"It's not only a problem with universal suffrage - it's about the limited freedom and legal system slowly being obliterated by these violent acts.
"The road ahead is long and tough, but we should retain our goal and keep walking on this bumpy road of democracy."
Other leading anti-establishment figures targeted in the past include media businessman Jimmy Lai, whose office and home were firebombed in January.
Kevin Lau, former editor of the liberal Ming Pao newspaper, was attacked by knife-wielding assailants in February last year.
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".
Organisers of the march set for Wednesday have distanced themselves from radical groups.
"For a couple of years there have been opposing groups protesting alongside the main march [but] we have been able to maintain the order," said Johnson Yeung, of march organisers Civil Human Rights Front.