Billionaire Silicon Valley investor Yuri Milner said Monday he had renounced his Russian citizenship.

"My family and I left Russia for good in 2014, after the Russian annexation of Crimea. And this summer, we officially completed the process of renouncing our Russian citizenship," the Moscow-born Milner tweeted.

Milner, founder of the internet investment firm DST Global and one of the original investors in Facebook, has been an Israeli citizen since 1999, DST Global said in a fact sheet on its website.

The venture capitalist and physicist has no assets in Russia and 97 percent of his wealth was created elsewhere, it said.

"Yuri has never met Vladimir Putin, either individually or in a group," it said.

Milner's non-profit Breakthrough Prize Foundation has condemned the Russian invasion of Ukraine.

"As the terrible war in Ukraine continues, with casualties and atrocities mounting, the Breakthrough Prize Foundation strongly condemns Russia's invasion of Ukraine and its unprovoked and brutal assaults against the civilian population," it said in a statement in March.

Milner's foundations have donated at least $11 million to help refugees from Ukraine and scientists forced to flee the country, according to DST Global.

Milner and the late British cosmologist Stephen Hawking in 2016 announced an ambitious space initiative for a mission to Alpha Centauri, the nearest star system to Earth, using tiny light-propelled, ultra-light space vehicles, or "nanocraft".

The pair also teamed up to launch a massive search for intelligent extraterrestrial life in a $100-million, 10-year project to scan the heavens, funded by Milner.