The EU country is on the front line in strengthening NATO's eastern flank following Russia's invasion of neighbouring Ukraine and has seen US and European military reinforcements arrive in recent weeks.

The IAR 330-Puma helicopter crashed on Wednesday in the area of Gura Dobrogei, 11 kilometres (seven miles) from an airfield, the defence ministry said.

All seven aboard, aged between 27 and 53, were killed.

The helicopter had been searching for a missing Soviet-era MiG 21 LanceR fighter jet, which lost contact and disappeared from the radar while on air patrol.

The missing jet was found overnight, having crashed near Cogealac, an uninhabited area near the Black Sea, the defence ministry said.

The 31-year-old pilot died, it added.

- Exercises cancelled -

The losses were the deadliest such incident in Romania since 2014 when a military helicopter crashed in the centre of the country, killing eight.

Military and religious ceremonies for the victims will be held in all Romanian military units on Thursday.

The helicopter pilot reported adverse weather conditions and had been ordered to return to base, according to the defence ministry.

All IAR 330-Puma and MiG LanceR aircrafts are grounded while the cause of the crash is being investigated.

The defence ministry said an air police exercise scheduled for Thursday was also cancelled. German, Italian and Romanian Eurofighter aircraft had been due to take part.

Defence Minister Vasile Dincu told local media there was "no evidence" to suggest a hostile attack behind the tragedy.

"The airspace is under surveillance, and nothing can pass without being noticed," Dincu said.

Twenty-two aircraft from Italy, Germany and the United States are currently deployed in Romania to protect airspace, according to the Romanian defence ministry.

Romania, a former member of the communist bloc now part of NATO and the European Union, has seen tens of thousands of refugees arrive since Russia invaded Ukraine last week.

- NATO's eastern flank -

Bucharest had repeatedly demanded reinforcements following months of growing regional tensions.

Its allies responded.

The United States sent a squadron of Stryker armoured vehicles and some 1,000 troops in recent weeks to a Romanian base near the Black Sea, adding to the 900 personnel already stationed in the country.

And over the past month, six Eurofighter Typhoon aircraft from Germany's air force joined four similar planes Italy dispatched before the crisis.

More than 500 French soldiers are being sent to the eastern European country this week.

Romania's Air Force still relies on the Soviet-era MiGs for air policing missions, although it is in the process of modernising its aircraft.

MiG 21 LanceR crashes occur occasionally.

In 2018, a Romanian Air Force pilot died after his MiG 21 LanceR crashed during an air show.

bur-jsk/jm

STRYKER