BEIJING: At least 12 gold miners trapped hundreds of metres underground in China for more than a week have sent up a note warning that they are injured, surrounded by water and urgently need medicine.

Twenty-two workers were trapped more than 600 metres from the mine's entrance after a blast eight days ago near Qixia city in eastern Shandong province.

After days without any signs of life, rescuers heard knocking sounds on Sunday afternoon as they drilled through the mine's shaft.

A note was sent up on a line from the depths below saying that at least a dozen of the miners are still alive, but that they urgently needed help as their health deteriorates.

"We are in urgent need of medicine, painkillers, medical tape, external anti-inflammatory drugs, and three people have high blood pressure," the note read.

The condition of the other ten workers is unknown.

Four people were injured, according to the note, which was crumpled, water-stained and scrawled in pencil on pages ripped out of a notebook.

"We wish the rescuers won't stop so that we can still have hope. Thank you," the note read.

The writer of the note asked rescuers to send down some medication from his car, and warned that there was a large amount of underground water where the miners are trapped.

Rescuers were later able to speak with some of the trapped workers after lowering a phone line into the mine, local officials said at a press conference Monday, without giving details of what was said.

Footage from state broadcaster CCTV showed rescue workers cheering as the knocking sound was detected and later hurrying to read the note which was taped to a line sunk below using a pneumatic drill.

Footage showed rescuers sending food and drinks attached to a wire down a small opening to the miners.

Hopes of a miracle rescue after a days-long ordeal triggered an outpouring of sympathy and encouragement on Chinese social media.

The hashtag "Qixia gold mine incident" was viewed 130 million times on popular social media site Weibo.

"I saw the note while I was watching the morning news and burst into tears," one Weibo user wrote.

"I hope they will rescue the trapped workers as soon as possible."

Some rescue workers wore fur hats to stave off the cold while others appeared covered in dust and grime from the rescue operation.

Rescuers intend to drill multiple tunnels into the mine to vent air as well as deliver supplies, CCTV said, while work continues on bringing the men back up to safety.

Chen Fei, a top city official, said the mission was a "race against time."

"We must win the race," he said at a press conference Friday.

The explosion badly damaged the communications system and exit ladder from the mine, which is owned by the Shandong Wucailong Investment Co. Ltd.

Two officials have already been sacked over the accident, while provincial authorities have opened an investigation into the cause of the explosion.

Mining accidents are common in China, where the industry has a poor safety record and regulations are often weakly enforced.

In December, 23 workers died after being stuck underground in the southwestern city of Chongqing, just months after 16 others died from carbon monoxide poisoning after being trapped underground at another coal mine in the city.