It will be "difficult" to raise hundreds of millions of pounds from private sources to help pay for flood defences over the next six years, MPs have warned.

The Government has pledged £2.3 billion in capital funding for flood defences to protect an extra 300,000 properties and cut flood risk by 5 per cent by 2021.

But success relies on £600 million funding from external sources, as well as 10% efficiency savings in the department responsible for flood management, the Department for Environment, Food and Rural Affairs (Defra), the MPs said.

With "relatively small amounts" of funding coming from the private sector so far, the parliamentary Environment, Food and Rural Affairs (Efra) Committee warned that it was unclear how the £600 million target would be met.

They also warned that funding for maintaining existing flood defences was at a "bare minimum" and called on the department to draw up "fully funded plans" for tackling a backlog of repairs and maintaining increasing numbers of defence schemes.

In a report on Defra's performance, the MPs also criticised a lack of transparency in the department over plans to cut its budget in coming years, slow progress on creating marine protected areas in the UK's seas and poor staff morale.

And they called on Defra to confirm whether it will continue with badger culling to tackle TB in cattle in Gloucestershire after the second year of the pilot scheme failed to meet requirements for the number of badgers which needed to be killed.

For flooding, the Government has implemented a "partnership funding" approach in which contributions to flood defences are drawn from outside Whitehall, including from businesses and local authorities.

But just £40 million of the £148 million secured up to 2014/2015 came from sources other than local government, the report said.

Efra committee chairwoman Anne McIntosh said: "The Government has committed £2.3 billion in capital funding for six years' investment aimed at protecting 300,000 properties, but that plan relies on external contributions of £600 million.

"We support the principle that the private sector should help to fund new flood defence schemes but we have repeatedly expressed concern about the relatively small amounts of private sector funding secured to date under the Partnership Funding approach, with only £40 million of the £148 million secured up to 2014-15 coming from sources beyond local government.

"It is unclear how the £600 million target can be met and we want Defra to demonstrate how it intends to obtain that money and to explain the impact on its investment programme if the money does not come forward."

A Defra spokeswoman said: "By the end of this financial year, the partnership funding approach we introduced in 2012 is expected to have raised £140 million. This compares with just £13 million in the previous four years.

"We are working closely with the Environment Agency to attract more investment and are introducing tax relief for business contributions to flood risk management projects from 2015 onwards to encourage more investment."

"In addition, we are making record levels of capital investment, spending £2.3 billion over six years in improving defences right up to 2021.

"This is in line with what the Environment Agency predicts will be the optimum investment for our flood defences over the next 10 years."