"Ahead of schedule, the UK-led Op Interflex has reached the milestone of 30,000 recruits trained in the UK since June 2022", the ministry said in a statement.
The total number of Ukrainian personnel trained since 2014 has topped 52,000.
The British defense ministry called the operation the largest training program for foreign troops in the UK since the Second World War.
"Today, NATO ally Romania has also confirmed its involvement, taking the total number of partner nations to ten," the statement read.
Other participants are Canada, New Zealand, Norway, Denmark, Finland, Sweden, Lithuania, the Netherlands and Australia, the ministry specified.
The UK has so far supplied Ukraine with main battle tanks, long-range cruise missiles, hundreds of thousands of artillery shells and more. Military aid totaled 2.3 billion pounds ($2.8 billion) in 2022, with the same amount pledged for this year. In September, UK Defense Minister Grant Shapps said that London would deliver "tens of thousands" more artillery shells to Kiev, and planned to have trained 30,000 Ukrainian soldiers by the end of 2023.
The Kremlin condemns Western military aid to Kiev, saying that it will lead to further escalation of the conflict in Ukraine and NATO's direct involvement in it.