Media playback is unsupported on your device Media caption Eurostar passengers arriving at St Pancras station in London told the BBC about their experiences

Eurostar passengers stranded overnight in Calais have returned to London, saying they were left on a dark train in "horrendous conditions".

A Paris-to-London service was forced to stop near Calais on Tuesday night after migrants got on to the tracks.

The train then developed a technical fault, with passengers finally arriving at St Pancras at about 11:00 BST.

Eurostar apologised and said it was advising customers on compensation for the delays.

Meanwhile, Prime Minister David Cameron said "taking more and more refugees" was not the answer to the EU's current migration crisis.

The EU should focus on bringing peace, stability and stronger economies to the countries that people were leaving, he said.

Hundreds of migrants have protested for a second day in Hungary after a decision to stop them travelling on to Germany and other EU countries, while at least 12 Syrians trying to reach Greece have drowned after the boats they were travelling in sank.

An image of one of the victims - a young boy lying face-down on the beach - has sparked an international outcry over the human cost of the crisis.

Image copyright SIMON GENTRY Image caption Passengers were left on the train for more than four hours

Eurostar passengers described a "horrendous" and "appalling" experience trapped on a train for up to 14 hours. Some said migrants were "knocking on the windows".

The Eurostar train was stopped following reports of people climbing on trains about 1.2 miles (2km) from the Channel Tunnel.

Two trains also had to turn back on Tuesday night - one to London and one to Paris - as the track was blocked between 21:45 and 02:23 local time.

'Bolted in'

Nadine Hickey, who was with her two young children after a visit to Disneyland Paris, said the experience was "one of the worst" of her life.

"We were in there in the dark for over four hours with no communication," she said.

Image caption Imogen Cuthbertson said her experience had been "horrendous"

Image copyright Simon Gentry Image caption Passengers were given thermal foil blankets after their Eurostar train was stranded at Calais station

Bridget Roussel, 52, from Greenwich, south-east London, said the conditions on board were "chaos".

"The lights went off and the air conditioning went off, it was so hot. The toilet by that time was so disgusting, it made me feel sick," she said.

Passengers also complained they were given very little information, and no food, then packed into a "freezing" station and given thermal foil blankets after the carriages were finally evacuated in Calais.

Michael Richardson, 45, from north London, who was travelling with his wife and two-year-old son said: "We were told the French army helicopter was searching using thermal imaging cameras.

"They were saying someone had smashed one of the windows."

'Steps on the roof'

Linda Roberts, 67, from Southfields, south London, said she saw a group of about six young men walking on the tracks.

"They were on the train, you could hear steps on the roof," she added.

A Eurostar spokeswoman acknowledged it had been a frustrating time for passengers, and apologised for the inconvenience caused.

"Our staff have been on hand today and through the night to provide as much support and care as possible to arriving customers and to advise on compensation," she added.

The current migrant crisis in Calais is part of a wider surge of people into Europe from north Africa and the Middle East.

Migrants camped near the city have attempted to stow away on lorries headed for the Eurotunnel and the ferry ports, and on the Le Shuttle trains themselves.

Image copyright Getty Images Image caption There are about 2,000 people camped at Budapest's Keleti train station, having bought tickets for onward journeys

Eurotunnel said most of the migrant intrusions were now happening outside the Channel Tunnel perimeter.

A spokeswoman said the company had reached an agreement with French national railway operator SNCF to help with the erection of some eight miles (13km) of high security fencing to begin "in the days ahead".

Last month, Home Secretary Theresa May warned the ongoing migrant crisis could shift from Calais to other ports, saying she was "well aware of the possibility of displacement".

Elsewhere, the Home Office said on Wednesday that 20 migrants had been found in the back of a lorry arriving at a ferry terminal in North Shields.