Foreign minister Sergey Lavrov has said Russia "is not to blame" for the nerve agent attack on an ex-Russian spy in the U.K., AP reports. The denial comes as the Kremlin has also asked the U.K. to open an investigation into the spy's daughter, per Reuters, and summoned the British ambassador to Russia, per the AP.

The backdrop: U.K. Prime Minister Theresa May addressed the House of Commons on Monday and said "the [British] government has concluded that it is highly likely that Russia was responsible for the act against Sergei and Yulia Skripal." She gave the Kremlin 36 hours to come up with a credible response. Former double agent Sergei Skripal and his daughter, Yulia, remain in critical condition after the poisoning.

The latest...

• Secretary of State Rex Tillerson, in Africa on a diplomatic trip, called the poisoning “an egregious act” and said it “appears that it clearly came from Russia," per NYT.
• More from Tillerson: “I’ve become extremely concerned about Russia ... We spent most of last year investing a lot into attempts to work together, to solve problems, to address differences. And quite frankly, after a year, we didn’t get very far. Instead what we’ve seen is a pivot on their part to be more aggressive.”
• His comments were notably stronger against Russia than the White House response. Sanders condemned the poisoning but said nothing about Russia's involvement.