British military aircraft were scrambled to investigate Russian planes which flew close to UK airspace, the Ministry of Defence (MoD) confirmed.

Officials said Typhoon aircraft were dispatched from Scottish base RAF Leuchars after the Russian presence was detected.

A defence spokesman said: "Typhoon quick reaction alert aircraft were launched today from RAF Leuchars to determine the identity of unknown aircraft that approached the Nato air policing area north of Scotland and could not be identified by other means.

"The aircraft were subsequently identified as Russian military aircraft. The Russian military aircraft remained in international airspace at all times as they are perfectly entitled to do so.

"Russian military flights have never entered UK sovereign airspace without authorisation."

Similar incidents happened eight times during 2013, an MoD spokesman said.

Today's operation comes after the MoD sanctioned a naval vessel to intercept a Russian ship as it came close to UK waters last week.

A defence spokesman tonight confirmed that as part of separate and routine activity, HMS Dragon, the Royal Navy's fleet-ready escort, sailed from Portsmouth on Good Friday to meet up with a Russian ship, the Vice Admiral Kulakov, which is transiting past the UK.

The spokesman said: "In what is a well established and standard response, the powerful Royal Navy Type 45 destroyer met its Russian counterpart and is now keeping an eye on its transit south."

Defence Secretary Philip Hammond said the operations should not raise alarm.

He said: " Recent events have increased awareness of Russian military activity, but we have always routinely intercepted, identified and escorted Russian air and naval assets that transit international airspace and waters within the UK's 'area of interest'.

"The Royal Navy and Royal Air Force will remain alert and ready to intercept any non-Nato forces in the area."