Rescue workers in China are still frantically digging to try to reach 33 miners trapped underground for a fifth day.

Three workers were reported killed on Tuesday when a section of a mine collapsed in a flood near the city of Xuzhou, in the eastern Jiangsu Province.

On Wednesday, 23 miners were rescued.

However on Saturday the official Xinhau news agency increased the number of those reported killed to seven.

"We are still digging, but no new progress has been made so far", said an official of the Xuzhou Coal Mine Group which operates the mine.

"It's hard to know how many are dead because no messages have been sent from the inside. Some of them must be still alive since we can still hear noises," he said.

Rescue workers have cut a narrow tunnel through debris and are attempting to feed oxygen, milk, glucose and water through to the trapped miners.

It is not yet clear whether the supplies have reached the miners.

Two rescue teams are continuing digging towards those trapped from different directions.