Kyiv has relied on billions of dollars in military aid from its Western backers to fight back against Russian forces, but has also invested heavily in its domestic arms sector.

"In the first half of this year alone, Ukraine produced 25 times more ammunition for artillery and mortars than in the whole of 2022," Zelensky told a defence forum in Kyiv.

Almost 300 weapons companies, both Ukrainian and foreign, were in Kyiv for the conference, Zelensky said.

Throughout the conflict, Ukraine's army has used a mix of Soviet-era weaponry, supplies donated by the West and some cutting-edge domestic equipment such as long-range attack drones.

Its troops have faced months-long ammunition shortages amid political wrangling in Washington over aid payments, which has underscored to Kyiv the importance of investing in its own production.

"In the extremely difficult conditions of a full-scale war, under constant Russian attacks, Ukrainians were able to build a virtually new defence industry. Today, everyone can see this new Ukrainian capability," Zelensky said.

Ukraine now has the capacity to produce four million drones a year, Zelensky said.

Drones have become crucial battlefield equipment for both Moscow and Kyiv. Small craft are used everyday for frontline reconnaissance while larger ones are packed with explosives and flown hundreds of miles into enemy territory.

Ukraine's Prime Minister Denys Shmygal told a government meeting that half of the ammunition Ukraine uses at the front was produced domestically.

But further boosting production inside Ukraine is complicated by the fact that the entire country is within range of Russian missiles.

Despite the challenges, Zelensky said the sector had achieved a remarkable turnaround.

"Years ago, the Ukrainian defence industry looked, unfortunately, helpless," he said. "But now it is an industry that is on its way to becoming a leader, at least in Europe."

Alongside long-range drones, Ukraine also produces the Neptune anti-ship missiles that have been used to hit several Russian vessels in the Black Sea.

And at the end of August, Zelensky announced the successful test firing of the first Ukrainian-made ballistic missile.