Rescuers racing to save sick man trapped 1 kilometre deep in Turkish cave

A researcher trapped deep in a Turkish cave has sent messages of hope and thanks despite being gravely ill.

In this screen grab from video, American caver Mark Dickey, 40, talks to camera next to a colleague inside the Morca cave near Anamur, southern Turkey. Source: AAP / Turkish Government Directorate of Communications

Key Points

• American researcher Mark Dickey was trapped in a cave in south Turkey.
• Rescuers from across Europe have rushed to his aid.
• The "highly trained" caver has sent out a video thanking the Turkish government.

Rescuers from across Europe have rushed to a cave in Turkey to try to save a US researcher who became trapped around 1 km below the surface after suffering stomach bleeding.

The European Association of Cave Rescuers said experienced caver Mark Dickey, 40, suddenly became ill during an expedition with a handful of others, including three other Americans, in the Morca cave in southern Turkey's Taurus Mountains.

In a video message from inside the cave and made available on Thursday by Turkey's communications directorate, Mr Dickey thanked the caving community and the Turkish government for their efforts.

Dickey said: "Hi. Mark Dickey from nearly a thousand metres."

"The caving world is a really tight-knit group and it's amazing to see how many people have responded on the surface."

"We're still waiting for communications actually to reach down here. So right now it's a day or two days of travel for information to get back and forth."

"I don't quite know what's happened, but I do know that the quick response of the Turkish government to get the medical supplies that I need, in my opinion, saved my life. I was very close to the edge."

Turkish and international cave rescue experts are working to save US caver Mark Dickey. Source: AAP / Mithat Unal

Dickey, who had been bleeding and losing fluid from his stomach, has stopped vomiting and has eaten for the first time in days, according to a New Jersey-based cave rescue group he is affiliated with.

It is unclear what caused his medical issue. The New Jersey Initial Response Team said Dickey is "very sick" and is located about 1,000 metres below the surface.

The group said the rescue will require many teams and constant medical care.

Communication with Mr Dickey takes about five to seven hours and is carried out by runners, who go from Mr Dickey to the camp below the surface where a telephone line to speak with the surface has been set up.

The New Jersey group says the cave is cold - about 4-6C. Dinko Novosel, a Croatian cave rescuer who is head of the European Association of Cave Rescuers, said it will be a challenge to successfully rescue Dickey.

The operation to bring him up from the depths involves rescue teams from Bulgaria, Croatia, Hungary, Italy, Poland and Turkey.

The European Cave Rescue Association said on its website Dickey experienced the gastrointestinal bleeding during his descent into the cave and he is unable to hoist himself out on his own,

Mark Dickey in the cave. Source: AP / Turkish Government Directorate of Communications

The group described Dickey as "a highly trained caver and a cave rescuer himself" who is well known as a cave researcher, or speleologist, from his participation in many international expeditions. He is secretary of the association's medical committee.

Experts say the rescue operation could take days or even weeks depending on conditions.