A sea of Russian flags, pro-Kremlin pop stars, and state television unexpectedly cutting President Vladimir Putin mid-speech: Moscow on Friday marked eight years since its annexation of Crimea from Ukraine, as its troops advanced further into the country.

Tens of thousands took part in an ultra-patriotic rally at Moscow's main Luzhniki stadium. Many wore a ribbon with the letter Z, which has become a symbol of support for the Russian army in Ukraine.

The event was heavily anti-Western and filled with Soviet nostalgia, as Russian authorities ramp up patriotism in response to being hit by massive international sanctions for Putin's Ukraine campaign.

President Vladimir Putin spoke at a concert marking the eighth anniversary of Russia's annexation of Crimea
President Vladimir Putin spoke at a concert marking the eighth anniversary of Russia's annexation of Crimea POOL via AFP / Ramil SITDIKOV

A stage at the centre of the stadium had a banner that read "For a world without Nazism" -- a reference to Putin saying he sent troops to Ukraine to "de-Nazify" the country.

The Russian leader took to the stage to chants of "Russia! Russia! Russia!".

He said Moscow did the right thing in 2014 by "pulling Crimea out of the humiliating state it was in when it was part of another state."

The banners behind the stage read "For the world without Nazism" and "For Russia"
The banners behind the stage read "For the world without Nazism" and "For Russia" POOL via AFP / Sergei GUNEYEV

He claimed Russia had vastly improved the infrastructure of the peninsula -- which has been isolated since the annexation.

Russian troops have entered Ukraine from several directions since Putin sent them in last month, including from Crimea.

Putin said that Moscow now aimed to "rid people from their suffering and genocide".

Tens of thousands people attended the concert
Tens of thousands people attended the concert POOL via AFP / Yevgeny BIYATOV

He invoked the Bible as he praised Russian soldiers, which he said were "heroically" fighting "shoulder to shoulder" in Ukraine.

Then Russian TV cut Putin mid-sentence, switching to showing a clip of patriotic music.

The Kremlin later said it was a technical glitch, and state television proceeded to show Putin's speech in full and him walking off stage about ten minutes later.

The letter 'Z' was in evidence at the rally. "Z", does not appear in the Cyrillic alphabet, but appeared weeks ago on military vehicles rolling towards Ukraine, possibly to distinguish them from Ukrainian forces and avoid friendly fire
The letter 'Z' was in evidence at the rally. "Z", does not appear in the Cyrillic alphabet, but appeared weeks ago on military vehicles rolling towards Ukraine, possibly to distinguish them from Ukrainian forces and avoid friendly fire AFP / STRINGER

Russian state television is tightly controlled and such interruptions are highly unusual.

Patriotic pop stars and the face of Russia's RT state television channel -- Margarita Simonyan -- took to the stage one by one to back Putin's actions in Ukraine.

"Mother Russia, take Donbas home," Simonyan told crowds, referring to the eastern Ukraine region taken over by separatists in 2014.

"This is for our boys who are fighting scum right now," Simonyan, whose channel has been banned in most Western countries after Putin sent troops to Ukraine, told cheering crowds.

Russia's outspoken foreign ministry spokeswoman, Maria Zakharova, also took the stage.

"We are a country and nation that safeguards peace and fights evil," she said.

Some of Russia's leading pro-Kremlin pop stars performed well known patriotic hits in support of the Russian army.

Pop star Oleg Gazmanov sang his "Made in USSR" hit, with lyrics that include claiming that Kazakhstan and the Baltics are "part of my country".

Luzhniki -- which hosted the 2018 World Cup final -- has a capacity of 81,000. There were also crowds on the pitch of the stadium and outside it.

Putin sent thousands of Russian troops into Ukraine in the early hours of February 24th, despite weeks of warnings that Russia would be hit with massive sanctions that would cripple its economy if he did so.