US Secretary of State Antony Blinken has arrived in Kiev in a show of support for Ukraine in its standoff with Russia and to push officials to tackle corruption.

His plane landed in the Ukrainian capital tonight ahead of a day that includes talks with President Volodymyr Zelensky.

The visit comes after Russia recently began withdrawing tens of thousands of troops it had massed on Ukraine's borders for war games that raised fears of an outbreak of fighting in the east of the country.

The United States has been an important ally to Ukraine since 2014 when Russia annexed the Crimean peninsula and pro-Kremlin separatists broke away from Kiev in an ongoing conflict that has claimed more than 13,000 lives.

Mr Blinken is the first senior US official to visit Ukraine since Joe Biden was inaugurated as president in January.

He is also scheduled to meet Prime Minister Denys Shmygal, Foreign Minister Dmytro Kuleba, and anti-corruption activists.

The secretary of state "will reaffirm unwavering US support for Ukraine's sovereignty and territorial integrity, especially in the face of ongoing Russian aggression", Acting Assistant Secretary for European and Eurasian Affairs Philip Reeker said last week.

He added that Mr Blinken would push for progress on reforms and anti-corruption efforts, initiatives Ukraine's Western partners have called for in return for economic support.

The visit is "a very good signal of support for Ukraine", said Kostyantyn Yeliseev, a former ambassador to the European Union who founded the New Solutions Center think tank.

Kiev "expects the American side to confirm its readiness to provide Ukraine with lethal military aid" and discuss Washington taking a greater role in peace negotiations.

Mr Yeliseev said that Kiev also hopes the visit will lay the foundations for a future visit by Mr Zelensky to the White House.

President of Ukraine Volodymyr Zelensky

Mr Zelensky, pointing to the Russian troop movements, said recently that Ukraine should be fast-tracked into the NATO military alliance.

The proposal was met with a cool response in Washington and opposed by western Europeans concerned about Russia's response.

The United States has however earmarked $408 million for Ukraine this fiscal year.

Meanwhile, a ceasefire that took hold in July in eastern Ukraine has fallen apart, with clashes increasing between Ukrainian forces and separatists since January.

President Biden has recently ramped up pressure on Russia, and comments he made likening his Russian counterpart Vladimir Putin to a killer were met with fierce criticism in Moscow.

But Mr Biden is also preparing for a proposed summit with Mr Putin this year in the hope of stabilising ties between Moscow and Washington.

His administration has also renewed pressure on Ukraine to root out corruption and improve governance.

Ahead of Mr Blinken's trip, the State Department criticised Ukraine for removing the head of state energy company Naftogaz, saying the shake-up showed "disregard for fair and transparent corporate governance practices".

Andriy Kobolev had reduced Ukraine's dependence on Russian gas deliveries and introduced reforms that improved the company's public image.

The US must show Kiev that Mr Kobolev's dismissal has consequences, the independent Ukrainian news website Yevropeiska Pravda said in an editorial this week.

It said his removal negated "one of the few successful reforms" carried out in Ukraine and would put to rest hopes in Kiev that President Biden might visit the country later this year.