Package, which could be confirmed on Monday, is expected to include munitions for long-range systems and armoured medical vehicles.
The United States is preparing a new $1bn security assistance package for Ukraine, which will include munitions for long-range weapons and armoured medical transport vehicles, according to Reuters news agency.
The package would be one of the largest so far and is expected to be announced as early as Monday, three sources briefed on the matter told Reuters.
The US has given about $8.8bn in aid to Ukraine since Russia’s invasion on February 24.
The officials, speaking to Reuters on the condition of anonymity, said that President Joe Biden had not yet signed the next weapons package, and cautioned that weapons packages can change in value and content before they are signed.
However, if signed in its current form, it would be valued at $1bn and include ammunition for High Mobility Artillery Rocket Systems (HIMARS), and National Advanced Surface-to-Air Missile Systems (NASAMS) as well as some 50 M113 armoured medical vehicles.
The Pentagon recently announced Ukrainians would be allowed to receive medical treatment at a US military hospital in Germany near Ramstein Air Base.
Last Monday, the Pentagon announced a separate security assistance package for Ukraine valued at up to $550m, which also included additional ammunition for HIMARS.
The White House declined to comment on the package.
HIMARS played a key role in the battle between Ukraine and Russia, which has settled into a war of attrition fought primarily in the east and south of Ukraine.
Moscow is trying to gain control of the largely Russian-speaking Donbas, comprised of Luhansk and Donetsk provinces, where pro-Moscow separatists seized territory after the Kremlin annexed Crimea to the south in 2014.
So far the US has sent 16 HIMARS to Ukraine and on July 1 promised to send two NASAMS.
The armoured personnel carriers outfitted with medical equipment could make the fight with Russia more survivable for Ukrainian troops who could then be sent to Germany for further medical treatment.
The Kyiv government said in June that 100 to 200 Ukrainian troops were being killed every day on the battlefield.