The Secretary of State for Environment, Food and Rural Affairs has called for urgent tests of a lake, following a seven-year-old boy's death.

Liz Truss wrote to the Environment Agency, specifically the chief executive, Paul Leinster, to formally ask for the tests.

Zane Gbangbola was taken to hospital with his mother Nicole Lawler, 37, and father Kye, 48, after being overcome by fumes when the basement of their £1m riverside property in Chertsey was filled with floodwater in February 2014.

The seven-year-old, who attended St George's Junior School, Weybridge, died and his father was left paralysed from the waist down.

A spokesman for the Environment Agency said: "This is a tragedy and our sincere sympathies are with the Gbangbola family. Along with other agencies we have worked with Surrey Police on its investigation and we now await the coroner's findings."

It confirmed a copy of the letter had been received, and the agency will be carrying out further testing for the presence of any toxins in the lake.

Writing to Zane's parent's local MP, Kwasi Kwarteng, Ms Truss said: "As a parent I am extremely saddened to hear in our recent meeting [November 2014] more details about this tragic case. It is clear that on the face of it a number of institutions have some important questions to answer and I was concerned to learn about the slow progress that has been made by a number of bodies in getting to the bottom of what happened."

She said the testing would be for toxins such as chemicals which react with water to release hydrogen cyanide gas, alongside an investigation into criticism by Zane's parents of poor communication from local Environment Agency staff.

Mr Gbangbola said: "This is what we have been calling now for 11 months - for the land to be tested behind our home. It has been that long and still we have no date for an inquest, no cause of death, and no answers over how our son died."

In November Zane's parents held a protest outside the Environment Agency, supported by designer Vivienne Westwood, and handed in a 16,000-signature petition demanding the truth about his death.

Police said Zane died from carbon monoxide, but his parents said this was impossible because their house was fully electric.

A spokesman from the Department for Environment, food and Rural Affairs said: "This is a tragic case and our sympathies go out to the family. The Environment Agency is responsible for regulating waste sites and along with other agencies worked closely with Surrey Police who investigated this matter."

Surrey Police found no criminal charges would be brought over Zane's death.

Mr Gbangbola said: "I am glad that Ms Truss is going something about it. The government needs to ensure British people something like this never happens again. We have lost a son - yet thousands of other people may unknowingly be at risk.

"There needs to be an urgent inquiry not just into why Zane died, but into historical landfill site in the UK and the consequences of them being flooded.

"Anyone who knew our Zane will know exactly why we need to get to the truth. He was a incredibly bright, generous, happy and life-loving boy who had such a wonderful future ahead of him. We cannot let his death be in vain."