Anti-war campaigners rallied outside 10 Downing Street, the working home of the British prime minister, in London on Monday to protest US military action against Venezuela.

Participating groups and trade unions said around 2,000 people took part in the demonstration. Similar gatherings were also seen across the United Kingdom on Monday evening in Manchester, Glasgow and Edinburgh.

Protesters, carrying Venezuelan, Cuban and Palestinian flags, chanted slogans, including "Hands off Venezuela", "No more kills, no more wars — Venezuela isn't yours", and "No blood for oil".

Placards reading "Special relationship? Just say no" were also seen among the demonstrators as they were upset with the United Kingdom's stance of not condemning the US military action. The term "special relationship" has frequently been used to describe the exceptionally close ties between the United States and the UK.

Elizabeth, a Venezuelan who has lived in the UK for years and whose family is now trapped in Venezuela because of the US strikes, called Washington's actions "imperialism", saying its intention is "purely" to "grab resources".

For so long, the US has treated Latin America as its playground, said Elizabeth, who refused to give her last name.

"The only thing different now is that (US President Donald) Trump is by far more open about it. The treatment that we have been receiving is very much like the word 'backyard'. There is no dignity. You feel humiliated. You feel degraded."

Jim Curran, a protester and chairman of the Irish Civil Rights Association, said the US has a long record of practicing the 19th-century Monroe Doctrine — a US foreign policy named after former president James Monroe that viewed Latin America as Washington's exclusive sphere of influence and justified US hegemony.

From invading territories to forcing regime changes in South America, Curran said the Monroe Doctrine is ultimately an "imperialist doctrine" as the US only seeks to dominate states with limited capacity to defend themselves.

"They would not attack bigger nations like Russia, China, India or maybe even Brazil. They are attacking the smaller nations," he said.

Elizabeth echoed the concern, saying the US had already set a precedent with the Gaza Strip.

"No one stopped (the US) a year ago, a year and a half ago, two years ago, when they started the horrendous things in Gaza, in Palestine. Who is going to stop them now?" she said.

"Why (did the strikes against Venezuela happen) now? Because now they are even more confident that no one is able to stop them."

'Disgusting silence'

The reactions from European politicians amount to "disgusting silence", Elizabeth added. "Well, you want to keep the hope, but it is difficult."

European leaders have reacted with references to international law and the United Nations Charter, while some statements stopped short of direct confrontation, which critics viewed as deference.

Belgica Guana Cole, an Ecuadorian protester, said she was concerned about what the future holds for the international community if such acts are not stopped.

"The world needs to stop this criminal offense against humanity. If we don't stop, this can happen in any part of the world. No one is safe from this criminal act."

Wang Jingli and Gao Kejing contributed to this story.