Pepper spray: safeguard of public order or instrument of torture?

It is banned as a weapon of war, and carrying it on the streets of Hong Kong is illegal for those not in uniform, so it is not surprising that the use of pepper spray by police is controversial.

The Hong Kong force yesterday defended its use of the spray - known as OC foam in police parlance - during student protests on Friday night, saying it was used to "guard the safety of people at the scene".

By contrast, Amnesty International says the use of the weapon is tantamount to torture. Under the 1926 Geneva Protocol and the Chemical Weapons Convention - signed by China and ratified in 1997 - its use in international warfare is banned.

Yet it is frequently used when protests in Hong Kong threaten to get out of hand.

"Police had no other options and had used OC Foam to stop … acts that showed disregard for public safety and public order," the force said after student democracy protesters rushed into the forecourt of government headquarters. Vinci Yim, a 22-year-old student at Baptist University, saw it differently. She said she was sprayed two or three times in the face.

Like others, Yim said she held her hands up to indicate that she was not pushing officers. "I said: 'We are just students. What have we done wrong?'... Then I was sprayed in the face," said Yim, lifting her arms to display red bruises. "I fell to the ground because I could not see."