The Great Belt Strait, which connects two major islands in the Scandinavian country and is the main shipping route to the Baltic Sea, is off limits until the problem is resolved.

Denmark's National Maritime Authority had earlier warned ships not to sail through the strait due to the risk of "falling missile fragments".

The Danish military said the problem occurred "during a mandatory test where the missile launcher is activated and cannot be deactivated" on the frigate.

Its statement added: "Until the missile launcher is deactivated, there is a risk that the missile can fire and fly a few kilometres away."

A report by the Norwegian Defence Ministry said the missile contains 150kg of explosives, and is not armed and will not detonate if it crashes into the sea.

A naval exercise was ongoing in the area, a navigational warning showed.

The warning covered an area some 2.5 miles south of the Great Belt Bridge, which crosses the strait between between the Danish islands of Zealand and Funen.

The 11-mile bridge remained open to traffic, its operator said.

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The strait's closure follows a turbulent week for the Danish navy after the government dismissed its top military official Flemming Lentfer on Wednesday.

His firing comes after another Danish frigate malfunctioned in the Red Sea last month following a Houthi militant drone attack.

Mr Lentfer failed to inform the ministry in detail about the incident on 9 March and was sacked due to a breach of trust, Defence Minister Troels Lund Poulsen said.