PARIS, March 13 (Xinhua) -- French Foreign Minister Jean-Yves Le Drian told his British counterpart Boris Johnson on Tuesday that France had "full confidence" in Britain rapidly establishing the truth in the saga of the former Russian spy and his daughter being poisoned.

During a phone conversation, Le Drian denounced the attack, which involved a military-grade nerve agent against former Russian intelligence officer Sergei Skripal and his daughter Yulia earlier this month.

"We have full confidence in the British investigation so that responsibilities can be established quickly," the French minister said, adding France stood against "impunity of those who resort to or develop toxic agents.

On March 4, Skripal and his daughter were found unconscious on a bench in a shopping center. They remain in a critical but stable condition.

British Prime Minister Theresa May on Monday said it was "highly likely" that Skripal had been targeted by a "military-grade nerve agent of a type developed by Russia".

She gave Moscow until midnight on Tuesday to explain the spy poisoning incident.

In Russia, Kremlin's spokesman Dmitry Peskov denied the country's involvement in the attack.