ST PETERSBURG (Reuters) - Aggressive U.S. tactics such as a campaign against Chinese telecoms firm Huawei will lead to trade wars - and possibly real wars - Russian President Vladimir Putin said on Friday, in a show of solidarity with China alongside its leader Xi Jinping.

In some of his strongest words on the subject, Putin accused Washington of “unbridled economic egoism”. He singled out U.S. efforts to thwart a Russian gas pipeline to Europe and a U.S. campaign to persuade countries to bar Huawei, the world’s biggest telecoms equipment maker, from supplying network gear.

His broadside, at an economic forum in St Petersburg on the same platform as Xi, was a clear show of unity with China at a time when Beijing is locked in a trade war with Washington and Moscow’s own ties with the West are at a post-Cold War low.

“States which previously promoted free trade with honest and open competition have started speaking the language of trade wars and sanctions, of open economic raiding using arm-twisting and scare tactics, of eliminating competitors using so-called non-market methods,” said Putin.

“Look for example at the situation around Huawei which they are trying not to just squeeze out, but to unceremoniously push out of the global market. It’s already being called the first technological war of the emerging digital era in some circles.”

The world risked slipping into an era when “general international rules will be exchanged for the laws of administrative and legal mechanisms ... which is how the United States is unfortunately behaving, spreading its jurisdiction over the whole world,” added Putin.

“...It’s a path to endless conflicts, trade wars and maybe not just trade wars. Figuratively speaking, it’s a path to battles without rules that pit everyone against everyone else.”

Putin also complained about the U.S. dollar, calling it an instrument of pressure whose role in the financial system should be reconsidered.

China’s Xi struck a more conciliatory tone, calling for world powers to protect the global multilateral trade system. Speaking through an interpreter, he said it was “hard to imagine a complete break” between the United States and China.

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“We are not interested in this, and our American partners are not interested in this. President Trump is my friend and I am convinced he is also not interested in this,” Xi said.

Russia has long complained about Western sanctions imposed on it over disputes including its behaviour in Ukraine. Moscow casts the restrictions as an attempt to contain its growth.

Washington has asked countries to reject Huawei technology in the development of new mobile phone networks, arguing that it could be vulnerable to Chinese eavesdropping. Huawei denies its equipment is a security risk.