Chinese Internet users have deluged the microblog of the Russian embassy in Beijing with thousands of abusive comments within days of its opening, just ahead of a visit to Moscow by China's new president Xi Jinping.
The Chinese Communist Party came to power in 1949 when its forces finally triumphed in the country's long civil war, and for a time it was closely allied with its ideological counterpart in the Soviet Union.
They later split, but since the collapse of the USSR commercial and political ties between China and Russia have grown, and the two countries now cooperate on a range of issues at the United Nations.
"Hello everyone! This is the Russian embassy! Today, we opened a weibo. We welcome your interest," the embassy said on Monday as it launched a verified account on Tencent Weibo, a Chinese site similar to Twitter.
Its cheerful greeting was not returned. By late Thursday, the site had seen more than 27,000 comments and retweets, the vast majority of them negative.
"Take back your communism because you don't even believe it yourself," read a post from a user identified as Xuyang.
"Down with the evil party! Down with the red devil! Down with the sect!", read another, adding an emoticon of a clenched fist.
Others pointed to old territorial disputes -- a large area of far eastern Russia was once Chinese, but ceded to the Russian Empire by the Treaty of Peking in the mid-19th century, and there were military clashes in 1969 over a border island.
Officially the rows have been settled, but one poster said: "Return Outer Manchuria! Take back that party!"
On Friday Chinese leader Xi Jinping starts his first overseas trip since becoming head of state, with Moscow his first stop for talks with President Vladimir Putin.
No-one from the Russian Embassy was available to comment.