Ukraine is set to receive at least 100 old Leopard 1 tanks from Denmark, Germany and the Netherlands.
According to a joint statement by the defence ministers of the three countries, they will provide refurbished Leopard 1 A5 battle tanks from industrial stocks.
A spare parts and ammunition package and the "required logistic support and training" will also be part of the support, the statement added.
German defence minister Boris Pistorius said the first 20-25 Leopard 1 tanks would be in Ukraine by the summer, reports said.
Belgium has shown interest in joining the Leopard 1 iniative, according to the joint statement.
The announcement of the Leopard 1 tanks comes after mounting pressure on Germany to send Ukraine tanks culminated in the country agreeing to send newer Leopard 2 main battle tanks to Ukraine.
In January, the German government said it would initially provide Ukraine with one company of Leopard 2 A6 tanks, which comprises 14 vehicles, from its own stocks.
The goal is to provide Ukraine with a total of two battalions – 88 tanks – with donations from other countries.
At the time, Prime Minister Rishi Sunak welcomed the move, saying in a tweet, alongside the UK's Challenger 2s, "they will strengthen Ukraine's defensive firepower".