The search for four British sailors missing in the Atlantic is being boosted by additional air support.

Relatives of the men said seven aircraft would be searching for signs of the 40ft yacht Cheeki Rafiki.

The development came after the captain of a catamaran told the US Coast Guard he spotted a plank and a piece of foam in the area where the yacht went missing.

The British sailors got into trouble as they were sailing back to the UK from an Antigua regatta and started taking on water 620 miles east of Cape Cod, Massachusetts, last Thursday.

The four men on board - experienced captain Andrew Bridge, 22, from Farnham in Surrey, and crew members James Male, 23, from Southampton, Steve Warren, 52, from Bridgwater, Somerset, and Paul Goslin, 56, from West Camel, Somerset - have not been seen or heard from since the early hours of Friday morning.

Relatives of all four men met Foreign Office officials in London today.

Graham Male, father of James, said: "It was a very constructive meeting, it really filled the families in with the detail.

"What we can say is the UK Government and the US Coast Guard are right behind us, which we're so grateful for.

"We know there's going to be some resources going out there. Of course it's a large area to cover. They are going to continue their support."

Cressida Goslin, wife of Paul, said three US military aircraft will join the search, alongside two Canadian planes, one from Britain and one from the US Coast Guard.

She added: "We're very pleased, it's wonderful news. I don't think anybody could be doing anything more than they are."

The families said they had no new information about the debris which was spotted by the skipper of the Malisi catamaran.

A spokeswoman for the US Coast Guard said: "I can confirm that we have received reports (of debris) from the sailing vessel Malisi. They have found some debris in the search area. We can't tell at this time if they are from the Cheeki Rafiki as there were no identifying marks on them.

"The debris was a plank of wood and a small piece of floating foam, but there was nothing identifying the Cheeki Rafiki. Obviously it is a possibility, and we are definitely treating it very seriously and incorporating that into our search, but I can't say for certain that it was from the Cheeki Rafiki."

The sailors' families are in discussions with a crowd-sourcing initiative set up by a satellite company. Tomnod, run by DigitalGlobe, allows people to view satellite photos online and tag objects of interest. It was previously used following Typhoon Haiyan and the disappearance of Malaysian Airlines flight MH370.

Mr Warren's daughter, Laura Carpenter, said: "It's a free website so you just sign up and then you can search images and you can tag if you see anything, then they send the co-ordinates to the coastguard or the yachts that are out there."

She said she hoped the system would be set up soon but acknowledged that it was a lengthy procedure.

Gloria Hamlet, Mr Warren's partner, remained hopeful the men would be found.

"If there's eyes out there looking for them then there's a chance," she said. "Hopefully today will be the day but we've got to wait and see.

"At the end of the day we're trying to be very grounded and trying to be very realistic, but you can't help but hope."