Ukraine has sacked two senior cyber defence officials, a government official has said, as prosecutors announced a probe into alleged embezzlement in the government's cyber security agency.

Yurii Shchyhol, head of the State Service of Special Communications and Information Protection of Ukraine (SSSCIP), and his deputy, Viktor Zhora, were dismissed by the government, senior cabinet official Taras Melnychuk wrote on Telegram.

Mr Melnychuk, the cabinet's representative to parliament, did not mention the reasons for the dismissals. Mr Shchyhol wrote on Facebook that he was confident he could prove his innocence, Interfax Ukraine reported. There was no immediate comment from Mr Zhora.

The SSSCIP is responsible for securing government communications and defending the state from cyberattacks.

News of the firings came less than an hour before anti-corruption prosecutors said they were investigating the head and deputy head of the SSSCIP over their alleged roles in a six-person plot to embezzle 62 million Ukrainian hryvnia (€1.57m) between 2020 and 2022.

Ukrainian soldier checks shells at his fighting position in the direction of Bakhmut

Authorities suspect the officials of buying software at an inflated price from two companies allegedly under their control in a sale that had been closed to other bidders, Ukraine's National Anti-Corruption Bureau said.

In a statement on Telegram, the SSSCIP said it was cooperating with investigators and that all agency procurement had been carried out legally.

Ukraine has stepped up efforts to curtail corruption as it pursues membership in the European Union, which has made the fight against graft a key prerequisite for negotiations to begin.

Recent targets for investigation have included a billionaire former patron of President Volodymyr Zelensky and the ex-head of Ukraine's Supreme Court. Both have denied wrongdoing.

In September, Mr Shchyhol told Reuters that Russian spies are using hackers to target computer systems at law enforcement agencies to identify and obtain evidence related to alleged Russian war crimes.

US Defence chief visits Ukraine to reassure Kyiv on support

Earlier, US Defence Secretary Lloyd Austin made an unannounced visit to Kyiv to reassure Ukraine that Washington will continue supporting its fight against invading Russian forces.

The United States has provided tens of billions of dollars in security aid for Ukraine and repeatedly pledged to back Kyiv for "as long as it takes," but opposition from hardline Republican politicians has raised doubts about the future of American assistance.

Mr Austin "travelled to Ukraine today to meet with Ukrainian leaders and reinforce the staunch support of the United States for Ukraine's fight for freedom," the Pentagon said in a statement on the trip, which was not previously announced due to security concerns.

"He will also underscore the continued US commitment to providing Ukraine with the security assistance it needs to defend itself from Russian aggression," it said.

The trip to Kyiv is the Pentagon chief's second since Russia launched a full-scale invasion of Ukraine in February 2022.

Washington is by far the biggest donor of military assistance to Kyiv, and a cut to American aid would be a major blow to Ukraine as it readies for the second winter of the war.

Mr Austin and Secretary of State Antony Blinken urged lawmakers during a hearing in October to sustain support for Ukraine, with the US defence chief saying that "without our support, (Russian President Vladimir) Putin will be successful."

'Smaller' aid packages

But some Republican politicians oppose continued aid, and new support for Ukraine was left out of a temporary deal passed by Congress last week to avert a US government shutdown.

Despite this, a senior US defence official told journalists that "we continue to believe that Congress will provide that support, and we are planning based on that conviction."

US assistance has not been halted and there is still previously authorised aid to draw on.

But Deputy Pentagon Press Secretary Sabrina Singh said earlier this month that assistance packages "have been getting smaller because we have had to meter out our support for Ukraine."

Deputy Pentagon Press Secretary Sabrina Singh

In addition to domestic US political opposition to continued aid, the devastating conflict between Israel and Hamas - and the spike in attacks on American forces in the Middle East that accompanied it - has drawn international attention away from Ukraine.

But the United States insists that it can provide assistance to both countries.

"On the issue of whether there is a competition or trade-off between US support for Ukraine's defence of its country and Israel's defence of its people, there is not," the senior US defence official said.

"There is some overlap but where there is overlap in certain kinds of ammunition ... there is no reduction in the provision of capabilities to Ukraine," the official added.

The United States has spearheaded the push for international support for Ukraine, quickly forging a coalition to back Kyiv after Russia invaded and coordinating aid from dozens of countries.

Ukraine's supporters have also provided training to Kyiv's troops, while the United States and other countries imposed tough sanctions on Russia, with targets including financial institutions, technology imports and energy exports.

Two dead after strikes in Kherson

Two people were killed early today after Russian forces shelled a parking lot in the southern city of Kherson, authorities said.

Regional prosecutors opened a war-crimes investigation into the artillery strike, which occurred at around 9am (0700 GMT) and injured one other person, the regional prosecutor's office reported.

Kherson Governor Oleksandr Prokudin said the two dead were drivers for "a private transport business".

Images posted on Telegram showed firefighters dousing cars that had been blasted apart, one day after a separate strike on the city wounded five people, including a 3-year-old girl.

Russian forces have regularly shelled Kherson from across the Dnipro River since the regional capital was deoccupied by Ukrainian troops in November last year.

Ukraine said last week it had secured a foothold on the eastern bank of the Dnipro and that its troops were trying to push Russian forces further back.