It was a moment of another shock as Air Algerie flight AH1020 signal an emergency landing but later disappears from tracking data but later was found

The Boeing 737-600 was flying from Algiers to Marseille when the emergency was announced

A passenger plane sparked a massive mystery after it declared a mid-air emergency and then disappeared from tracking devices before landing safely.

The Air Algerie Boeing 737-600 took off from Algiers this afternoon on a flight to Marseille but let out an emergency call shortly after take-off.

Flight tracking data showed the plane turning around and heading back towards the point where it took-off.

Before the plane arrived however, it disappeared from tracking systems sparking a mystery that lasted almost an hour.

Plane tracking site Flight Radar 24 listed the plane's status as "unknown" before revealing to its followers that it did not believe the plan had crashed.

It was later revealed that coverage for ADS-B - a system where satellite navigation is used to determine a plane's location is limited in the area in which the plane 'disappeared'.

Posting to Twitter, the group said: "We believe Air Algérie AH1020 to be a *coverage issue* NOT a missing aircraft. Our ADS-B coverage in Algeria is limited."

Moments later, media in Algeria announced the plane had landed safely in Algiers having suffered technical failure while thousands of feet in the sky.

The initial worries were sparked when the plane completely disappeared from a number of flight tracking websites.

While some flight enthusiasts claimed the plane may have not been picked up below 17,000ft if it landed safely, Others have expressed surprise that no news of the plane's arrival back at Algiers had been released.

The flight took off at around 1.30pm local time and was due to arrive in Marseille just after 4pm.

The plane in question has space for 123 seats - although it is not yet known how many were occupied by crew and passengers.