US reported to be preparing another $800m military aid package to Ukraine

More artillery and tens of thousands of shells may be sent as Russia steps up pressure on besieged city in eastern Ukraine

A sign that reads 'Children' is fixed on to a car windscreen riddled with bulletholes in Irpin, Ukraine. AFP

A woman weeps next to her husband's coffin at a cemetery in Irpin. AFP

Residents walk amid debris of a charred Russian tank next to destroyed houses in the village of Zalissya. AFP

Volunteers distribute food to residents in Zalissya. AFP

A man walks past a damaged apartment building in the southern port city of Mariupol. Reuters

Tamara, 71, cries in front of a destroyed apartment building in Mariupol. Reuters

Local residents push a cart with a child past destroyed buildings in Mariupol. Reuters

A record player sits among debris inside an apartment in Mariupol. Reuters

Residents carry belongings past a destroyed building in Mariupol. Reuters

Security guards help an injured man following a Russian bombing of a factory in Kramatorsk. AP

A man receives first aid treatment. AP

Soldiers collect explosives after recent battles in the village of Moshchun, close to Kyiv. AP

The Komodor logistics park lies in ruins after being bombed and burnt during the Russian invasion near Makarov. Getty Images

A room in a kindergarten stands windowless in Makarov. Getty Images

A vehicle draped with a Ukrainian flag passes over a war-damaged bridge in Makarov. Getty Images

A man sits in a basement that was used as a bomb shelter in the village of Kukhari. EPA

Local residents clean the area around a destroyed farm in Kukhari. EPA

Nadia looks at her husband's coffin at a cemetery in Bucha. He was killed during the war. AFP

Mangled buildings in Irpin point to the ravages of the ongoing war. Getty Images

A burnt apartment tower in Irpin. Getty Images

Family members grieve during the funeral of Ruslan Nechyporenko, 47, in Bucha. Getty Images

An abandoned Russian military position in Borodyanka town near Kyiv. EPA

Heavily pregnant Dr Marta Kopan, who fled Kyiv with her husband Dr Maxim Motsya and their three-year-old son Makar, narrates their ordeal at a relative's place in Lviv. AP

A Ukrainian officer searches for unexploded explosives as he passes by an Antonov An-225, the world's biggest cargo aircraft, destroyed during the war on the outskirts of Kyiv. AP

A woman stands amid the destruction caused when a civilian building was hit by a Russian missile in Lviv, western Ukraine. Getty Images

Ukrainian soldiers on an armoured personnel carrier, near the front line with Russian troops, in Izyum district, Kharkiv region, north-eastern Ukraine. AFP

Ukrainian refugees arrive at the Siret border crossing between Romania and Ukraine. AFP

Ukranian soldiers in a trench look out across the front line near Kharkiv. AFP

Cars destroyed in Russian attacks, in Irpin, near Kyiv. The scene of fierce fighting, the town was occupied by Russian forces. Reuters

Damaged and destroyed vehicles at Illich Iron and Steel Works Metallurgical Plant, in an area controlled by Russian-backed separatists in besieged south-eastern city Mariupol. AP

Russian military vehicles in an area controlled by Moscow-backed separatists near Mariupol. AP

An elderly woman waits do be evacuated from a hospice in Chasiv Yar city, in Donetsk, eastern Ukraine. At least 35 residents have been helped to flee from the region that has been under attack for weeks. AP

A Ukrainian Interior Ministry serviceman collects unexploded shells, grenades and mines, following fierce fighting in Hostomel. AP

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The US is preparing to send more aid to Ukraine, matching the $800 million in assistance President Joe Biden pledged last week, media outlets reported on Wednesday.

Details were still being discussed, CNN said.

NBC News said the aid could include more artillery and tens of thousands of shells as fighting in eastern Ukraine intensifies.

When asked by reporters on Tuesday if more weapons were to be sent, Mr Biden said: “Yes".

The president discussed additional security and economic and humanitarian assistance with G7, EU and Nato leaders on Tuesday.

They also talked about providing more ammunition, White House Press Secretary Jen Psaki said.

Word of additional military assistance came as Russia pushed for victory in the Ukrainian port city of Mariupol. A surrender ultimatum to Ukrainian troops expired on Wednesday.

Pentagon spokesman John Kirby said the US is moving as quickly as possible to deliver assistance.

“We know that the time is not our friend. And the clock is a bit of an enemy here, too,” he said.

Mr Biden last week announced an $800m package that included helicopters, 18 howitzers and 40,000 artillery rounds. The Pentagon said on Monday the first shipments had arrived at Ukraine's borders.

The US military began training Ukrainian troops on the use of howitzer artillery, a senior US defence official said on Wednesday. The training, which is being conducted outside Ukraine, will take about one week.

"It's a smallish number of Ukrainians, a little bit more than 50," the official said.

Pentagon spokesperson John Kirby told reporters that should Ukraine need any more artillery rounds, "the United States will be right at the front of the line doing what we can to help get them there."

Ukraine has also received aircraft and aircraft parts from partner countries, Mr Kirby said, but Washington has not provided aircraft.

The US has so far provided $3.2 billion in assistance to Ukraine.

Mr Biden is scheduled to meet Defence Secretary Lloyd Austin, chairman of the Joint Chiefs of Staff Gen Mark Milley and other military figures on Wednesday.

Mr Austin earlier met Polish Defence Minister Mariusz Blaszczak at the Pentagon.

Agencies contributed to this report