The campaign group said a dozen activists poured 300 litres of biodegradable dye into the pond outside the embassy in southwest London, using containers bearing the words "Stop Arming Israel".

"Five people have so far been arrested nearby on suspicion of criminal damage and conspiracy to cause criminal damage," the Metropolitan Police force said.

Greenpeace UK said six people had been arrested, including one of its heads but the police did not provide the names of those detained.

Will McCallum, Greenpeace UK's co-executive director was arrested on suspicion of conspiracy to cause criminal damage, the group said in a statement.

"These arrests are further proof that the right to protest is under attack in the UK. This protest used biodegradable pond dye that is designed to disperse and wash away naturally," said co-executive director Areeba Hamid.

Police said the pond could be reached by a public footpath and that "there was no breach or attempted breach of the secure perimeter" of the embassy site in Nine Elms.

Greenpeace is calling for the UK and US governments to impose an arms embargo on Israel, which renewed its offensive in Gaza last month.

UK campaigners have criticised the arrests of climate and pro-Palestinian protesters under beefed-up anti-protest powers granted to the police.

Last month, a court cut by one year a five-year jail term imposed on Just Stop Oil's 58-year-old co-founder Roger Hallam accused of conspiracy for planning to block the M25 motorway in an online call.