A Russian politician is warning Britain against escalating the crisis over the poisoning of a former Russian spy.

Moscow and London have both ordered diplomats to be expelled in the deepening dispute.

Vladimir Dzhabarov, deputy chairman of the foreign affairs committee in the upper house of the Russian parliament, spoke on Saturday after Russia ordered 23 British diplomats to leave the country and that the British Council in Russia to be closed.

Britain this week ordered 23 Russian diplomats to leave the country, saying that Russia was not co-operating in the case of Sergei Skripal and his daughter, both found poisoned by a nerve agent that British officials say was developed in Russia.

β€œIt is possible that (Britain) will continue to respond; we are ready for this. But London must understand that this will not do anything, it is useless to talk with Russia with such methods,” Mr Dzhabarov was quoted as saying by the state news agency RIA Novosti.