Romania says a Russian drone has breached its airspace - the second NATO country to report such an incursion.

Romanian fighter jets were in the air monitoring a Russian attack in Ukraine on Saturday and were able to track the drone near Ukraine's southern border, the defence ministry said in a statement.

Ukrainian President Volodymyr Zelensky said the incursion could not be a mistake - it was 'an obvious expansion of the war by Russia'. Moscow has not commented on the Romanian claims.

On Wednesday, Poland said it had shot down at least three Russian drones which had entered its airspace.

In its statement, Romania's defence ministry said it detected the Russian drone when two F-16 jets were monitoring the country's border with Ukraine, following 'Russian air attacks on Ukrainian infrastructure on the Danube'.

The drone was detected 20km (12.4 miles) south-west of the village of Chilia Veche, before disappearing from radar.

However, it did not fly over populated areas or pose imminent danger, the ministry said.

The EU's foreign policy chief, Kaja Kallas, called the incident 'yet another unacceptable breach of an EU member state's sovereignty'.

Poland also responded to concerns over Russian drones on Saturday. 'Preventative operations of aviation - Polish and allied - have begun in our airspace,' Prime Minister Donald Tusk said in a post on X.

'Ground-based air defence systems have reached the highest state of readiness.'

Earlier this week, Russia's defence ministry stated there had been 'no plans' to target facilities on Polish soil.

Belarus, a close Russian ally, claimed the drones which entered Polish airspace on Wednesday were an accident due to jamming in their navigation systems.

In response to the latest drone incursion, President Zelensky emphasized that the Russian military knows exactly where their drones are headed and have requested Western countries to tighten sanctions on Moscow.

US President Donald Trump expressed willingness to impose tougher sanctions on Russia if NATO countries cease purchasing its oil.

Since Russia's full-scale invasion of Ukraine in February 2022, tensions in the region have escalated significantly.

Recent movements orchestrated by nations such as Poland and the Czech Republic reveal a collective effort to bolster air defenses and respond effectively to potential incursions as the war in Ukraine persists.