Ukrainian army says immediate clashes have broken out on the streets of Ukraine’s second city after landing of Russian paratroopers.

The Ukrainian military says immediate clashes have erupted after Russian paratroopers landed in Ukraine’s second largest city of Kharkiv on the seventh day of Russia’s full-scale invasion of its neighbour.

“Russian airborne troops landed in Kharkiv … and attacked a local hospital,” the army said on Wednesday, in a statement on the Telegram messaging app. “There is an ongoing fight between the invaders and the Ukrainians.” According to Anton Gerashchenko, adviser to the Ukrainian interior minister, a fire broke out on Wednesday in the barracks of a flight school in the city following an air raid. “Practically there are no areas left in Kharkiv where an artillery shell has not yet hit,” he said in a statement posted on Telegram.

The city’s governor, Oleg Synegubov, also said on Telegram that seven people were killed in an attack on a government building and that 24 people were wounded. The reports could be independently confirmed. Russia says it is only targeting Ukraine’s military infrastructure, air defence and air forces with high-precision weapons.

Hostilities have simmered for years but tensions are now escalating amid fears of a Russian invasion.

Kyiv, Ukraine – According to Washington, Russia has amassed more than 100,000 Russian soldiers on the border with Ukraine and in annexed Crimea in recent weeks.

This has stoked fears in Kyiv and the West that the Kremlin may start a new war with its neighbour and former province that chose to break away from Moscow’s political orbit.

Earlier this month, a top Ukrainian military expert told Al Jazeera that Russia could invade Ukraine as early as January, unleashing a “brief and victorious” war. But Russia denies it is planning an invasion. Moscow says it can move Russian troops wherever it wants and that any of its acts are defensive. Russian officials, including President Vladimir Putin, have for their part warned NATO against expanding eastwards. So, what is at the heart of the conflict that has been going on for more than seven years?

What is now Ukraine, Russia and neighbouring Belarus were born on the banks of the Dnieper River, almost 1,200 years ago in Kievan Rus, a medieval superpower that included a huge chunk of Eastern Europe. But Russians and Ukrainians parted ways linguistically, historically and, most importantly, politically.

Putin has, however, claimed repeatedly that Russians and Ukrainians are “one people”, part of the “Russian civilisation” that also includes neighbouring Belarus. Ukrainians reject his claims. Ukraine went through two revolutions in 2005 and 2014, both times rejecting Russia’s supremacy and seeking a path to join the European Union and NATO. Putin is particularly enraged by the prospect of NATO bases next to his borders and says Ukraine joining the US-led transatlantic alliance would mark the crossing of a red line.

A British man has been arrested in Germany on suspicion of spying for Russia.

German federal prosecutors said the man - named only as David S - worked at the British embassy in Berlin.

He allegedly passed documents to Russian intelligence "at least once" in exchange for an "unknown amount" of money.

He was arrested in Potsdam outside Berlin on Tuesday and his home and workplace have been searched.

A spokesman for Germany's foreign ministry quoted by AFP news agency said Berlin was taking the case "very seriously", and said spying by "a close alliance partner on German soil is unacceptable".

The arrest was the result of a joint UK-German investigation, the statement read.

It was intelligence-led and had been going on for some time leading up to the arrest, the BBC's Security Correspondent Gordon Corera says. MI5 and other UK agencies, as well as British police, had been working with the Germans to learn as much as they could about the alleged activity.