BERLIN — A meeting between Germany's foreign minister and Hong Kong activist Joshua Wong will damage its relations with China, Beijing's ambassador to Berlin said on Wednesday, in an unusually direct verbal attack on an important trade partner.

The ambassador added that the Foreign Ministry in Beijing had summoned the German envoy in protest at the meeting — a statement later confirmed by Germany's foreign ministry.

At a time when Hong Kong is being rocked by protests, pro-democracy activist Wong arrived in Berlin on Monday night and German Foreign Minister Heiko Maas received him.

"What happened now, I unfortunately have to say, will have negative consequences on bilateral relations and the Chinese side has to react," Ambassador Ken Wu told reporters, according to an official German translation.

Hong Kong, a former British colony, was returned to China in 1997 under a "one country, two systems" formula that guarantees freedoms not enjoyed on the Communist mainland, including an independent legal system.

The unrest, at times violent, in Hong Kong over the last few months was prompted by anger over planned legislation to allow extraditions to China, but has widened into calls for democracy and for Communist rulers in Beijing to leave the city alone.

After his arrival in Berlin, Wong said Hong Kong was a bulwark between the free world and the "dictatorship of China". .

"After his arrival we took note that unfortunately certain politicians — and I will say very openly that it is Foreign Minister Maas himself — as well as some members of parliament met with Joshua Wong," said the Chinese ambassador.

"We don't know what goal these politicians have. Are they actually seriously concerned about Hong Kong's freedom, democracy and rule of law or they want to add fuel to the fire and thereby make political capital out of it?"

The dispute between Germany and China comes days after Chancellor Angela Merkel returned from a trip there. She said earlier she had told Chinese leaders that upholding human rights was indispensable.

The ambassador said the countries were important partners.

"We have a very good and long tradition of cooperation. We also have realistic needs to approach each other," he said.

Germany, whose firms have been caught up in the crossfire of the US-China trade conflict, traded almost 100 billion euros ($109.87 billion) in goods with China in the first half of 2019.

China has accused the United States, Britain and other Western countries of fomenting the Hong Kong unrest.

"China's sovereignty and security must be respected. I therefore advise politicians against covering up violent crimes and meddling with Hong Kong's and China's internal affairs," said the ambassador. — Reuters