Amnesty International and Human Rights Watch called on Thursday for the warring parties in Ukraine to respect human rights and fulfill their obligations under international law, including protecting civilian lives and property.

"Following Russia's attack on Ukraine this morning, Amnesty International calls for unequivocal respect for human rights and compliance with international humanitarian law" and "recalls that the lives of civilians, their homes and infrastructure must be protected at all costs," the organization said in a statement released this Thursday and quoted by Lusa.

Also the executive director of Human Rights Watch (HRW), Kenneth Roth, deplored the "declaration of war against Ukraine" made today by Russian President Vladimir Putin, stressing that there are "international law obligations" that must be met.

"With new details about what is happening on the ground emerging by the minute, the international community is struggling to find ways to respond and Human Rights Watch, which has been covering this war for eight years ... emphasizes that there are several paths to justice for any war crimes and crimes against humanity," Kenneth Roth wrote on the social network Twitter.

"Our greatest fears have come true," admitted Amnesty International's Secretary General Agnès Callamard.

"After weeks of escalation [of the conflict, a] Russian invasion has begun that is likely to have horrific consequences for human lives and human rights," he said.

Noting that it had already begun to receive reports of indiscriminate use of weapons by the Russian army, Amnesty International reiterated its call for all sides to protect "civilian lives, homes and infrastructure" and allow "access for humanitarian agencies to assist civilians affected by the hostilities."

Russia invaded Ukraine early Thursday morning, carrying out air strikes across the country, including in the capital, Kiev, and advancing with ground forces on three fronts: from the north, east, and south of the country.

The invasion was explained by Russian President Vladimir Putin with the need to protect ethnic Russian civilians in the breakaway republics of Donetsk and Lugansk, which he recognized as independent on Monday.

After the recognition, Putin authorized the Russian army to send a "peacekeeping" force to Donetsk and Lugansk, noting on Wednesday that the leaders of the self-proclaimed pro-Russian separatist republics had asked for help to "repel the aggression" of the Ukrainian military.

The West accuses Moscow of breaking the Minsk Accords, signed by Kiev and the pro-Russian separatists in Donetsk and Lugansk, under the auspices of Germany, France and Russia.