PARIS, March 30 (Xinhua) -- France's Foreign Ministry said on Friday that it regretted Russia's decision to expel four French diplomats.

"Russia's decision to expel four French embassy staff from Russia does not surprise us. We regret this and want to point out that to this day Russia has refused to give any explanation about the attack in Salisbury," the ministry said.

Despite the diplomatic row over the poisoning affair, "France reiterates its commitment and willingness to engage a constructive dialogue with Russia on all international issues," the French Foreign Ministry added.

Russian former double spy Sergei Skripal and his daughter were found unconscious on a bench in a shopping center in the southern British city of Salisbury on March 4. They were poisoned with a nerve agent in the first such attack in a European country since World War Two.

The British government accused Russia of involvement in the nerve toxin attack on the ex-Russian double spy Sergei Skripal and his daughter, which left both of them critically ill, but the Russian authorities have denied the accusation.

On Monday, France told four Russian diplomats to leave the country within a week in "full solidarity" with Britain that accused Moscow of poisoning one of its former agent on British territory.

Earlier on Friday, Moscow expelled 59 diplomats from 23 countries in retaliation to the coordinated move to knock out Russian diplomats by dozens of western countries.

In a separate statement, the Russian Foreign Ministry said it also summoned the British ambassador and informed him that Britain has to downsize its diplomats stationed in Russia to the same level as Russia has in Britain within a month.

Earlier this month, more than two dozens of countries announced the expulsion of around 150 Russian diplomats over the poisoning of Sergei Skripal and his daughter with a nerve agent.

Tensions between Russia and western countries have exacerbated over the ongoing exchange of diplomatic sanctions.