Police said Monday they will no longer stand guard outside London's Ecuadorian Embassy where WikiLeaks founder Julian Assange took refuge in 2012, but will strengthen a "covert plan" to prevent his departure.

"The Metropolitan Police Service (MPS) has today... withdrawn the physical presence of officers from outside the Embassy," police said in a statement.

"Whilst no tactics guarantee success in the event of Julian Assange leaving the embassy, the MPS will deploy a number of overt and covert tactics to arrest him."