New Delhi, Feb 24 (IANS): Ukraine was under siege on Thursday after Russian President Vladimir Putin announced he was invading in what he termed a "special military operation", sending in tanks from the northern border with Belarus in a combined Russian-Belarussian offensive, and launching attacks from the east and south, including on the capital Kiev, a Daily Mail report said.

Hundreds of Ukrainians were killed in the onslaught, the Daily Mail quoted the Interior Ministry in Kiev as saying, and videos on social media showed the scale of the invasion.

Five Russian jets and one helicopter were shot down over the east of the country, near Kharkiv, Ukraine's military said.

In his announcement on early Thursday morning, Putin insisted that Russia was only attacking military installations, and were avoiding populated areas. But Ukraine's officials said there had already been heavy casualties.

Ukraine's border force said that their posts in the north have come under attack from both Russian and Belarussian forces - a hugely significant development, meaning Russia is not acting alone, and is attacking from all sides, the Daily Mail reported.

The livestream video of the invasion from Belarus was taken at the Senkivka, Ukraine crossing with Veselovka, Belarus. The column was seen entering Ukraine at 6.48 a.m., CNN reported.

A Ukrainian government spokesman confirmed that Russia had invaded over the Belarus border as well, only 120 miles from Kiev.

He said: "The state border of Ukraine was attacked by troops from Russia and Belarus. At about 5a.m., the state border of Ukraine, in the area with the Russian Federation and the Republic of Belarus, was attacked by Russian troops supported by Belarus."