Belfast’s famous Harland & Wolff cranes are set to be "at their busiest for many years" after undergoing a comprehensive modernisation programme.

The iconic yellow gantry cranes, known as Samson and Goliath, will be refurbished at a cost of £3.1 million by owners Navantia UK.

Engineers will overhaul the engines of both cranes and replace the catenary cables responsible for supplying them with electricity.

Structural and electrical repairs will also be completed on both of the Belfast structures.

Work has already commenced on Goliath, the older of the cranes, built in 1969 with a height of 96 metres.

Once finished, the refurbishment will shift to Samson, the crane situated closer to the sea, installed in 1974 at 106 metres.

Each of the cranes is capable of lifting 840 tonnes, an amount equivalent to four Boeing 747 jumbo jets.

Work on Samson and Goliath is part of a £98.5 million recapitalisation of Harland & Wolff Belfast, which will prepare the yard for naval and commercial shipbuilding projects.

Harland & Wolff has begun a programme to build three fleet solid support ships for the Royal Fleet Auxiliary – which will provide supplies to naval ships at sea, and will be the second largest vessels in the armed forces behind the Queen Elizabeth class aircraft carriers.

Carlos Lopez Carregado, general manager at Harland & Wolff, described Samson and Goliath as “symbols of Belfast”.

“We know that the city is proud of them, and this major mechanical, electrical, hydraulic and fabric maintenance project will restore them to their absolute best,” he said.

“We will be replacing parts, updating technology and testing them to see that they can lift at full capacity, and we will be treating them with utmost respect

“The cranes are sophisticated pieces of machinery capable of carrying enormous weight.

“They will need all of their strength to lift blocks for the fleet solid support vessels, and for future ships which we anticipate building in Belfast.

“You can expect to see Samson and Goliath swing into action soon – they are about to be at their busiest for many years.”