A second spell of floods in less than a month has spread across parts of Bangladesh, killing seven people and leaving thousands stranded, officials said on Monday.

They said the overall death toll from flooding since July had risen to 840.

The weather continued to worsen on Monday with moderate to heavy showers, meteorology officials said. They forecast more rain under the influence of a very active monsoon that will last until end of the month.

The current floods, which began four days ago, forced over half a million from their homes.

Worst affected were farmers who had replanted crops lost in earlier flooding.

Agriculture officials said they were assessing damage to rice -- the country's main staple -- and other crops.

(Additional reporting by Abdus Shahed Montu in Kurigram)