Lifeboats were scrambled after thousands of Tamil protesters calling for international action to enforce a ceasefire in Sri Lanka threatened to throw themselves into the River Thames.
Four Royal National Lifeboat Institution (RNLI) lifeboats were on standby along with police, fire and the harbour master’s vessels, amid concern the demonstrators would attempt to jump en-masse into the river.
Police said the rally began at 4pm yesterday and around 3,000 people were still gathering today outside the Houses of Parliament at the junction of Bridge Street and Westminster Bridge.
The protest comes as Sri Lankan government forces close in on Tamil Tiger rebels.
A Scotland Yard spokeswoman said the protest was peaceful and there had been no arrests so far.
She said: “We are working with other emergency services including the RNLI and our own marine support unit.”