Image copyright Reuters Image caption Among the targets is Igor Sechin, who has worked for Vladimir Putin since the early 1990s

The US has imposed sanctions on seven Russian individuals and 17 companies it says are linked to President Vladimir Putin's "inner circle".

The White House said the move was a response to "Russia's continued illegal intervention in Ukraine".

Those targeted include Igor Sechin, head of oil giant Rosneft, and Sergei Chemezov of the hi-tech firm Rostec.

The announcement comes after the mayor of Kharkiv, a city in eastern Ukraine, was shot and critically wounded.

Analysis The most eye-catching name on the new sanctions list is one of the hard men of Russian politics, Igor Sechin. A former intelligence officer, and once President Putin's closest ally in the Kremlin, he now runs Rosneft - the huge state-controlled oil company. Alexei Pushkov, who heads the Russian parliament's foreign affairs committee and often speaks for the Kremlin to English-language broadcasters is also on the list, as are the deputy prime minister who was in charge of the Sochi Winter Olympics and the head of the Kremlin bodyguards. Seventeen Russian companies face new sanctions, too. All are linked either to President Putin's childhood friends and judo partners Arkady and Boris Rotenberg or to another close friend and billionaire Gennady Timchenko - or to Bank Rossiya, which the US government claims is the personal bank for senior Russian officials. Officials targeted by sanctions

Hennadiy Kernes was recovering after an operation to repair damage to the chest and abdomen, but his life remained in danger, his office said.

Mr Kernes used to be a supporter of former pro-Moscow President Viktor Yanukovych. He then dropped his support for Mr Yanukovych in favour of a united Ukraine.

Monday also saw pro-Russian separatists seize a local government building in Kostyantynivka, a town in the eastern Donetsk region.

In Donetsk itself, pro-Russian activists armed with clubs and chains attacked a pro-unity rally. A number of people were injured in the clash.

Western countries accuse Russia of actively supporting the activists in Eastern Ukraine - a claim denied by Moscow.

Separatists were also continuing to detain about 40 people in the town of Sloviansk, including journalists, pro-Kiev activists and seven military observers linked to the Organisation for Security and Co-operation in Europe (OSCE) as well as three members of Ukraine's security service, officials in Kiev said.

At an OSCE meeting in Vienna, Russian ambassador Andrei Kelin said Moscow was taking "steps" to secure the observers' release. But the area around Sloviansk was very tense and it had been "extremely irresponsible" to send them there, he added.

UN Secretary General Ban Ki-moon later called for the immediate and unconditional release of the observers.

Media playback is unsupported on your device Media caption Sarah Rainsford saw pro-Russians clash with a group marching for a united Ukraine

Separately, Russian Defence Minister Sergei Shoigu in a phone call with his US counterpart Chuck Hagel said Russian troops had returned to their permanent positions after conducting military exercises on the border with Ukraine.

But he did not say whether the overall number of Russian troops deployed in the region - said to be around 40,000 - had been reduced.

Meanwhile, Mr Hagel warned that Russia's continued aggression would result in more diplomatic and economic pressure.

'Additional costs'

The US and EU first imposed visa bans and asset freezes on a number of senior Russian officials and companies after Moscow annexed Crimea from Ukraine last month.

On Thursday, the White House said it was adding to its sanctions list "in response to Russia's continued illegal intervention in Ukraine and provocative acts that undermine Ukraine's democracy".

It accused Russia of "doing nothing to meet the commitments it made" at a meeting with Ukraine, the US and EU in Geneva on 17 April, which it said had included refraining from violence or provocative acts.

Russian Deputy Foreign Minister Sergei Ryabkov said Moscow's response would be "painful for Washington".

He told the Interfax news agency the Kremlin was "disgusted" by the sanctions.

Media playback is unsupported on your device Media caption One pro-Russian in eastern Ukraine told the BBC's Steve Rosenberg: "Maybe we'll celebrate New Year... in Brussels or Berlin"

Image copyright Reuters Image caption A number of people were injured in clashes in the eastern city of Donetsk

Image copyright AP Image caption Pro-Russian separatists seized a local government building in Kostyantynivka on Monday

Image copyright AP Image caption Western nations accuse Moscow of supporting the separatists, including those in Sloviansk

Image copyright Reuters Image caption Hennadiy Kernes was reportedly out cycling in Kharkiv when he was shot in the back

Among the seven government officials facing a US asset freeze and visa ban, two are seen as long-time allies:

Mr Sechin is a former KGB officer and was deputy chief of staff during Mr Putin's first two presidential terms, when he masterminded Russia's energy policy

Mr Chemezov is described by the US as a trusted ally dating back to the 1980s

Alexei Pushkov is chairman of the committee of international affairs of Russia's lower house of parliament, the State Duma

Most of the 17 companies targeted are linked to Arkady and Boris Rotenberg and Gennady Timchenko - individuals targeted in the previous sanctions list.

The latest measures also targets some hi-tech exports that "could contribute to Russia's military capabilities".

Meanwhile, diplomats in Brussels said EU governments had reached a preliminary agreement to impose similar sanctions on another 15 people as part of expanded sanctions against Russia. The names are expected to be released on Tuesday.