Ukrainian President Volodymyr Zelensky on Wednesday vowed a "strong response" after gunmen opened fire on a car carrying his senior aide, in what officials said was possible retaliation for a push to rein in oligarchs.

More than 10 bullets hit a black Audi carrying Zelensky's advisor Sergiy Shefir during an attack near the village of Lisnyky, south of the capital Kiev, around 10 am (0700 GMT) Wednesday.

The 57-year-old former scriptwriter and longtime associate of comedian-turned-politician Zelensky escaped unharmed but his driver was "seriously injured", the interior ministry said.

The shooting was one of the most high-profile assassination attempts in Ukraine's modern history and came after the country's 43-year-old leader promised to reboot the political system and tackle the influence of powerful oligarchs.

"Saying 'hello' to me by shooting out of the forest at my friend's car is weak," Zelensky said in a video statement from New York.

"The response will be strong."

Zelensky, who is in New York for the UN General Assembly, said it was not yet known who was behind the attack.

But he added: "This does not affect the course that I have chosen with my team -- towards changes, towards bringing the economy out of the shadows, towards fighting criminals and large, influential financial groups".

Authorities opened an attempted murder investigation. Photos released by officials showed a limousine with bullet holes along its bonnet and the driver's door.

Shefir called the attempt on his life an effort to "intimidate" the presidency.

Police said they were considering political motives.

The aide may have been targeted for his work, or as part of a bid to pressure Ukraine's top leadership or destabilise "the political situation in our country," national police chief Igor Klymenko told reporters.

The US and UK embassies in Ukraine condemned the attack.

"Criminal violence, including for political ends, is never justified. We wish the driver injured in the attack a quick and full recovery," the US mission said on Twitter.

The British ambassador to Ukraine, Melinda Simmons, tweeted that she was "very worried" and wished Shefir's driver a speedy recovery.

Photos published by officials showed a black Audi with bullet holes along its bonnet and on the driver-side door Photos published by officials showed a black Audi with bullet holes along its bonnet and on the driver-side door Photo: UKRAINIAN INTERIOR MINISTRY PRESS SERVICES / Handout

He told reporters any attempt to intimidate the president would fail. "He's chosen the right path," Shefir said.

He admitted however that the attack was "a bit scary".

"We were driving and suddenly there were shots," Shefir said, praising his chauffeur for continuing to drive despite being wounded.

The driver was operated upon and his life was not in jeopardy.

Police said they did not rule out the involvement of security services of foreign countries.

Ukraine's army has been battling Moscow-backed separatist fighters in two breakaway regions bordering Russia since 2014, when the Kremlin annexed the Crimean peninsula. The war has left more than 13,000 people dead.

The Kremlin denied any role in Wednesday's attack.

"Of course, this has nothing to do with the real state of affairs," said Kremlin spokesman Dmitry Peskov, accusing Ukraine of habitually looking for a "Russian trace".

Vitaliy Sych, editor-in-chief of Ukrainian magazine Novoye Vremya, said an attempt on the life of a president's aide was "unprecedented".

"I wonder who dared to do this and why," he said on Facebook.

This year Zelensky ordered his government to put together a register of oligarchs -- a list of tycoons who influence media and politics in the country. The names, however, have yet to be revealed.

Shefir was born in the industrial central city of Kryvyi Rig and studied to be a metallurgist, but as a student began doing comedy for the popular KVN show with his brother.

In 2003, he co-founded a production company called "Kvartal 95" with Zelensky, who was elected president in 2019.

Shefir produced and wrote the "Servant of the People", a television show in which Zelensky portrayed a schoolteacher who becomes president and which launched his political career.