Migrant boat disaster: Charity predicts 2,500 children could die this year unless a unified rescue mission is resumed in the Mediterranean

Britain is preparing to dispatch one of its biggest warships to tackle the urgent refugee crisis in the Mediterranean as campaigners warn up to 30,000 migrants, including 2,500 children, could die this year unless rescue operations are restarted immediately.

The deployment of HMS Bulwark a 176-metre launchpad for helicopters and small vessels is close to being sign-off after ministers backed a “more formidable operation on the sea” in response to the scores of migrant deaths in recent days.

Campaigners will attempt to intensify pressure on European Union leaders meeting in Brussels this week to restart search and rescue operations immediately. Justin Forsyth, Chief Executive of Save the Children, said the meeting would see the EU “hold the lives of thousands of desperate people in their hands”.

The charity predicts 2,500 children could die in the region this year unless a unified rescue mission is resumed immediately. “With every day that they prevaricate and delay restarting search and rescue operations, the risk grows that more people will die as they try to reach Europe,” she said.

“We cannot allow 2015 to be the deadliest year in the Mediterranean yet. We must get agreement at Thursday’s meeting to scale search and rescue back up to 2014 levels."

As more than 460 migrants prepare to land in Augusta, on the eastern coast of Sicily, new testimony is emerging of the tragedy earlier this week that claimed the lives of more than 800 migrants after the vessels they were travelling in sunk some 24 hours after leaving the coast of Libya.

One 18-year-old passenger from Somalia said more than 800 people were loaded on the boat with no food or water and some were people were locked below. It was when a call for help was issued and “people saw the lights of the rescue boats everyone began to move to one side and the boat inclined to one side and then it turned over completely", he said.

The attempt to cross the Mediterranean has become one of the great humanitarian crises of recent years giving rise to an industry of traffickers and harrowing tales of those who never live to make the journey. The death toll from capsizing disasters stands at 1,727 so far in 2015 - 30 times higher than the 56 fatalities by 21 April last year, according to the International Organisation for Migration. At the current rate the total for this year could reach 30,000.

In November the Italian authorities ended their Mare Nostrum programme, which had been designed to rescue migrants adrift in the Mediterranean. Britain also declined to join an expanded version of the EU’s border protection scheme last year.

Diplomats are now understood to be considering more pro-active options to help with the hundreds of migrants arriving in Lampedusa, Sicily, Calabria and Apulia amid growing concern over the spread of violence and terrorism in Libya. Deputy Prime Minister Nick Clegg said abandoning search and rescued was a mistake. “I think, with hindsight, that was not the right decision,” he told Channel 4 News. “But even if you return to that old search and rescue system, that still doesn't provide you with a solution, a European solution, to a very real problem - which is thousands of people in wretched circumstances travelling huge distances, exiting ports in North Africa in the hands of illegal human smugglers and traffickers and perishing on the high seas in the Mediterranean."

An MoD spokeswoman said it was "looking at options but no decisions have been taken".