Ukrainian President Volodymyr Zelenskyy has warned of new threats to his country. He says the Russians have purchased Shahed drones from Iran to make up for a deficit in their arsenal, and that they are also in negotiations to buy missiles.

Zelenskyy made the comments in a speech on Thursday during a visit to Estonia.

Ukrainian forces have shot down thousands of Shahed drones, which have been called "suicide" drones because they zero in on their targets and explode on impact.

British media report that Iran has developed another drone that Russia could use for both attack and reconnaissance. That model is believed to be fitted with technology to target British and US rocket systems.

Zelenskyy said the Russians have also received more than one million artillery shells from North Korea. Ukrainian officials claim to have found missile fragments that look "very similar" to parts of shells seen in military parades in North Korea.