British troops would not fight Russian forces in Ukraine, and that recent reinforcements were firmly within the borders of NATO members, Prime Minister Boris Johnson said on Tuesday while he also warned Russian President Vladimir Putin that he will have more NATO, not less.

"These are nothing more than defensive measures, which have been the essence of NATO for more than 70 years," he said during a visit to Estonia where Britain has deployed more troops.

"I want to be crystal clear finally, on that point, we will not fight Russian forces in Ukraine and our reinforcements like these reinforcements here in Tapa are firmly within the borders of NATO members and they are profoundly the right thing to do."

The shelling of the Ukrainian city of Kharkiv by Russian forces is an atrocity reminiscent of the attacks on Sarajevo by the Serbs in the 1990s, Johnson also said, adding such attacks were uniting the world against Russia.

Asked about the shelling of Kharkiv, Johnson said it was "absolutely sickening."

"It reminds me, if anything, if you remember the shelling of Sarajevo market by the Serbs, the shelling of innocent people in Bosnia, it has that feel to me of an atrocity committed deliberately against a civilian centre," Johnson said.

"I think people's stomachs are being turned by what's happening, and they're seeing it's necessary to stand up against Russian aggression (and) to support the Ukrainians."

If Russian President Vladimir Putin achieves his goal of ousting the government in Kyiv, the humanitarian and rights crises in Ukraine "will only get worse," the top U.S. diplomat also warned Tuesday.

U.S. Secretary of State Antony Blinken warned the U.N. Human Rights Council (OHCHR) that Russia's "premeditated, unprovoked and unjustified attack on Ukraine" was creating dire human rights and humanitarian crises there.

In a pre-recorded video, he also questioned whether Russia should be allowed to hold onto its seat on the Geneva-based council after launching its full-scale invasion of Ukraine on Feb. 24.

He decried that Moscow's "violations of international humanitarian law mount by the hour," pointing to the many civilians killed and well over half a million who have fled the country in a matter of days.

But, he warned, "if President Putin succeeds in his stated goal of toppling Ukraine's democratically-elected government, the human rights and humanitarian crises will only get worse."

Blinken pointed to the situation on the Crimean peninsula, which Moscow annexed in 2014.

There, he charged, "Russia's occupation has come with extrajudicial killings, enforced disappearances, torture, arbitrary detention, the persecution of ethnic and religious minorities, and the brutal repression of dissent.

"The Kremlin is also ramping up its repression within Russia," Blinken warned.

He said that "even before the invasion, it was shuttering human rights organizations and harassing, poisoning, and imprisoning anti-corruption activists and political opponents."

And since the invasion began just six days ago, "authorities reportedly have detained thousands of Russians peacefully protesting the invasions, as well as journalists covering the demonstrations," he added.

The top U.S. diplomat called on the council to "send a united message that President Putin should unconditionally stop this unprovoked attack ... and immediately withdraw Russian forces from Ukraine."

He also demanded, "steps to hold the perpetrators accountable."

Blinken voiced outrage that a member of the top U.N. rights body would carry out such a "flagrant assault on Ukraine's sovereignty."

"One can reasonably ask whether a U.N. member state that tries to take over another U.N. member state, while committing horrific human rights abuses and causing massive humanitarian suffering, should be allowed to remain on this council," he said.

Meanwhile, Russian Foreign Minister Sergey Lavrov on Tuesday urged Ukraine to take seriously the peace talks with Russia, "show independence and contractual capacity."

Speaking at the meeting of the OHCHR in Geneva via video conference, Lavrov said if agreements are achieved between Russia and Ukraine, they must avoid the fate of the Minsk Agreement on the Ukrainian crisis, which was never implemented.

Lavrov said the situation in the world is not improving, but getting worse due to the efforts by the U.S. and its allies to promote "rules-based order."

"What 'this order' turns out to be for human rights is clearly seen in the example of Ukraine," he said.

Lavrov said the 2014 coup in Ukraine led to the civil war, claiming that Putin decided to recognize the rebel regions of Ukraine and to launch a special military operation "to protect the residents" of Donetsk and Luhansk.

"The purpose of our actions is to save people by fulfilling our allied obligations, as well as the demilitarization and denazification of Ukraine so that this will never happen again. This is especially relevant in the light of an attempt to draw Ukraine into NATO.

"As you know, at the request of (Ukraine's President Volodymyr) Zelenskyy, negotiations between representatives of Russia and the delegation of Kyiv began. I hope that the Ukrainian side is aware of the seriousness of the situation, is aware of the need to show independence and contractual capacity, and will avoid repeating the history of the Minsk agreements," he said.

The Western reaction shows that its goal in Ukraine was to create an anti-Russian platform, he added.

"The U.S. and its allies, which are responsible for the killing of hundreds of thousands of people in Yugoslavia, Iraq, Libya, and Afghanistan, and the violation of human rights and international humanitarian law, are once again applying double standards," he said.

Lavrov called the Western sanctions "illegal" and urged to end "the arrogant philosophy of the West, based on a sense of its own superiority and exclusivity."

"The sovereign equality of states is a key principle of the U.N. Charter. It fully applies to the work of the UNHRC (OHCHR). Russia is always open to an equal, mutually respectful discussion on any issues, ready to find a fair balance of interests," he said.

Also, Belarusian leader Alexander Lukashenko said on Tuesday that he had asked Putin to deploy an additional S-400 missile complex west of Minsk, the RIA news agency reported, citing another news agency, Belta.

The complex is needed to defend the territory of Belarus, Lukashenko was quoted as saying.