Russia has defied all threats of Western sanctions on Friday regarding the ongoing controversy over the&nbsp;poisoning of the Kremlin critic, Alexei Navalny.

After Germany declared that it has&nbsp;"unequivocal evidence" that Navalny was poisoned, western leaders expressed shock and asked for Kremlin to come clean upon the matter.

Vladimir Putin-led Russia, however, has denied all accusations. So much so, a Russian toxicologist said Navalny's health could have deteriorated due to dieting or stress.&nbsp;

"The patient used diets to lose weight," chief regional toxicologist Alexander Sabayev told local media.

<a href="https://www.wionews.com/world/eu-urges-russia-to-cooperate-in-navalny-probe-threatens-restrictive-measures-325084">Also read:&nbsp;EU urges Russia to cooperate in Navalny probe; threatens 'restrictive measures'</a>

"This situation could have been provoked not only by diets, it could have also been provoked by possible instances of drinking to excess which we don't know about. It could have been provoked by stress and fatigue," he added.

"Any external factors could have triggered a sudden deterioration. Even a simple lack of breakfast."

However, NATO is now pressing for an urgent international probe into this matter, and has asked Kremlin&nbsp;to reveal its Novichok nerve agent programme to the global chemical weapons watchdog.

NATO called an emergency meeting on this matter and&nbsp;alliance chief Jens Stoltenberg said all countries were united in&nbsp;condemning this "horrific" attack on the&nbsp;44-year-old opposition politician.

<a href="https://www.wionews.com/world/head-of-world-chemical-arms-watchdog-expresses-concern-over-navalnys-poisoning-case-325029">Also Read:&nbsp;Head of world chemical arms watchdog expresses 'concern' over Navalny's poisoning case</a>

"The Russian government must fully cooperate with the Organisation for the Prohibition of Chemical Weapons on an impartial international investigation," Stoltenberg said.

"We also call on Russia to provide complete disclosure of the Novichok programme to the OPCW."

Russia has further declined all accusations saying,&nbsp;"A whole number of theories including poisoning were considered from the very first days," Dmitry Peskov,&nbsp;Kremlin Press Secretary said. "According to our doctors, this theory has not been proved."

Russia has defied all threats of Western sanctions on Friday regarding the ongoing controversy over the poisoning of the Kremlin critic, Alexei Navalny. After Germany declared that it has "unequivocal evidence" that Navalny was poisoned, western leaders expressed shock and asked for Kremlin to come clean upon the matter.

Russia has defied all threats of Western sanctions on Friday regarding the ongoing controversy over the poisoning of the Kremlin critic, Alexei Navalny. After Germany declared that it has "unequivocal evidence" that Navalny was poisoned, western leaders expressed shock and asked for Kremlin to come clean upon the matter. Vladimir Putin-led Russia, however, has denied all accusations. So much so, a Russian toxicologist said Navalny's health could have deteriorated due to dieting or stress. "The patient used diets to lose weight," chief regional toxicologist Alexander Sabayev told local media. Also read: EU urges Russia to cooperate in Navalny probe; threatens 'restrictive measures' "This situation could have been provoked not only by diets, it could have also been provoked by possible instances of drinking to excess which we don't know about. It could have been provoked by stress and fatigue," he added. "Any external factors could have triggered a sudden deterioration. Even a simple lack of breakfast." However, NATO is now pressing for an urgent international probe into this matter, and has asked Kremlin to reveal its Novichok nerve agent programme to the global chemical weapons watchdog. NATO called an emergency meeting on this matter and alliance chief Jens Stoltenberg said all countries were united in condemning this "horrific" attack on the 44-year-old opposition politician. Also Read: Head of world chemical arms watchdog expresses 'concern' over Navalny's poisoning case "The Russian government must fully cooperate with the Organisation for the Prohibition of Chemical Weapons on an impartial international investigation," Stoltenberg said. "We also call on Russia to provide complete disclosure of the Novichok programme to the OPCW." Russia has further declined all accusations saying, "A whole number of theories including poisoning were considered from the very first days," Dmitry Peskov, Kremlin Press Secretary said. "According to our doctors, this theory has not been proved."

Russia defies West sanctions after NATO's emergency meeting over Navalny

The Kremlin has dismissed accusations that President Vladimir Putin sanctioned the poisoning of critic Alexei Navalny.

Navalny case: Kremlin rejects allegation over suspect poisoning

After German doctors declared that Russian Opposition leader Alexei Navalny was poisoned, Kremlin today dismissed accusations of Putin's involvement.

Kremlin dismisses Navalny poisoning; US calls for 'full and transparent investigation'

Russian Opposition leader Alexi Navalny who was admitted in a German hospital after he slipped into a coma in Russia indicated "poisoning with a substance from the group of cholinesterase inhibitors", the hospital said on Monday.

Russian Opposition leader Navalny poisoned with cholinesterase inhibitors, says German hospital