China said on Thursday it acted in accordance with the law over the execution of four Canadian citizens in recent weeks.

Canada's Foreign Minister Melanie Joly said in Ottawa on Wednesday that China had executed four Canadian citizens in recent weeks, defying pleas from Ottawa for leniency.

"We strongly condemn the executions that did happen against Canadians in China," Joly said.

She said she was unable to discuss details of the case due to privacy requests from the families.

Beijing suggested on Thursday the Canadians had been convicted over narcotics offences, saying "... combating drug crimes is the common responsibility of all countries."

"China is a country under the rule of law," said Foreign Ministry spokeswoman Mao Ning.

Beijing, she said, "treats defendants of different nationalities equally without discrimination" and "handles cases fairly in strict accordance with the law."

China "protects the legitimate rights of the parties concerned as well as the consular rights of the Canadian side, in accordance with the law," Mao added.

Beijing also defended the executions in a statement sent to Canada's Globe and Mail newspaper.

"Drug-related crime is a severe crime recognised worldwide as extremely harmful to the society," the embassy statement said.

"China always imposes severe penalties on drug-related crimes and maintains a 'zero tolerance' attitude towards the drug problem." (AFP)