Murky floodwater is slowing moving towards the (heart )of the Thai capital Bangkok as thousands of people ignore orders to evacuate the city.

Relief workers are distributing aid to evacuation centers in (central) Bangkok, but they say they are struggling to reach residents still refusing to leave their homes.

"I believe thousands of people are in their homes and are still not evacuating," relief co-ordinator Rungsun Munkong told CNN. "(They) possibly will be (stranded) with little food and water as time goes by."

He says other agencies have attempted to reach people trapped in tower blocks "but the scale is just massive."

"I think it will be difficult down the road to get (help to) these people," Munkong says, adding, "People need clean water, that's the first important thing. Cooked ready-to-eat food is also quite important, baby milk and so on."