A body is thought to have been spotted in the search for five people including two Britons lost in the South China sea.
Rescuers are desperately trying to find the group after the yacht they were sailing from Hong Kong to the Philippines went missing during a typhoon.
The Foreign Office said it was "liaising urgently" with local authorities after the vessel disappeared as it travelled to Subic Bay, north west of Manila.
The Philippines coast guard said it had spotted what appeared to be a floating body, orange objects and an oil slick from the air, about 250 miles from the city of Laoag.
However it has not been confirmed if they were from the Europa yacht, spokesman Armand Balilo said.
One of the Britons on board the vessel was named as Robin Wyatt, who lived in the Philippines and was described as an "experienced offshore sailor".
In a statement, the Royal Hong Kong Yacht club said: "The boat is new and on board are the skipper Robin Wyatt and four other crew members, all of whom are very experienced seamen; each having crossed the China Sea a number of times."
The Royal Hong Kong Yacht Club said an emergency radio beacon was activated on the yacht on Saturday, indicating it was experiencing difficulties.
A Foreign Office spokesman said: "We can confirm a yacht with two British nationals on board has gone missing between Hong Kong and Subic Bay.
"We are liaising urgently with the local authorities concerning search and rescue operations and provide support to the families."
The Philippine coastguard said the yacht, which was also carrying an American, a Canadian and a Filipino, disappeared at the time tropical storm Mujigae hit the region.
The 60-foot long vessel left Hong Kong on Thursday and failed to arrive in Subic Bay as expected over the weekend.
According to its website, Europa Yachts Ltd was founded by Mr Wyatt in Hong Kong in 2012 before the company expanded into the Philippines.
Mr Wyatt has 25 years' experience selling new and second hand yachts across Asia, it added.
Tropical storm Mujigae blew out of the northern Philippines on Saturday and intensified at sea into a powerful typhoon before slamming into the southern Chinese province of Guangdong the following day. At least 10 people were killed in the two countries, Chinese and Philippine authorities said.