Hong Kong pro-democracy student leader Joshua Wong was barred Tuesday from entering Malaysia because of fears he would threaten ties with China, the country's police chief said.

Wong was the teenage face of the "Umbrella Movement", which brought parts of Hong Kong to a standstill for more than two months late last year with mass rallies calling for fully free leadership elections.

Wong had been planning to give talks on democracy in China, from the massacre of pro-democracy protesters in Beijing's Tiananmen Square in 1989 to Hong Kong's Umbrella Movement, according to the Scholarism student protest group he founded.

But Malaysia's Inspector-General of Police Abu Bakar Khalid said the purpose of Wong's visit was to explain how he had organised demonstrations in Hong Kong.

"We were afraid that what he was going to speak about would harm our security," he told AFP.

"He was also going to speak about China. We know his anti-Chinese speeches. We do not want him to jeopardise our ties with China," Khalid said.

Democracy activists reject Beijing's restrictions on a proposed public vote for Hong Kong's leader in 2017, which stipulate that candidates must be vetted by a loyalist committee.

Khalid said Malaysian police had asked the immigration department to stop Wong entering the country.

"We do not need him in Malaysia as Wong is an undesirable element," he said.

Wong was sent back to Hong Kong on the same Dragonair flight on which he arrived.

On his return, he said officials in Malaysia had taken his passport and air ticket for half an hour before telling him he must return to Hong Kong "immediately".

"I asked what's the reason? Were there any documents? And the representative only said it was a government order," he said.

"I asked if there was any detailed information about the government order and they didn't want to respond. They tried to grab my arms and take me away."

Wong added: "I don't understand how there is any relation between the Umbrella Movement and Malaysia's national security."

Wong's visit came less than two weeks before the 26th anniversary of the Tiananmen Square massacre on June 4.

Hong Kong commemorates the anniversary each year with a candlelit vigil attended by thousands.

Wong called on the Hong Kong government to look into his case, saying it was an infringement of his right to travel freely.

Hong Kong's security bureau said in a statement it respects "the right of other jurisdictions in exercising immigration control and making decisions in accordance with their laws".