The future of the House of Lords would be called into question if ministers press ahead with plans to curtail its powers, the Lord Speaker has said.

Baroness D'Souza said the Lords "should be free to scrutinise, to question and to hold the government to account".

A review of the Lords was launched after it blocked government plans to cut tax credits in October.

Lord Strathclyde, who led the review, said there was no suggestion the Lords' powers would "fundamentally change".

During the last parliamentary session, the Lords inflicted 60 defeats on the government, including several changes to the housing bill last week.

In return ministers have been clear they are looking into ways of making that harder.

'Free to scrutinise'

The review recommended taking away the absolute veto the House of Lords has over laws, called statutory instruments, and instead creating a new procedure allowing them to send secondary legislation back to the House of Commons to "think again".

Under the recommendation, they would be allowed to do this only once, enabling the House of Commons to have the final say and push through its agenda even if the Lords disagreed.

Baroness D'Souza, who is standing down from the role of speaker in the summer, told the BBC's Sunday Politics: "Obviously we would expect the Lords to want to retain their power to scrutinise... if you start curtailing or eroding or limiting the power of the Lords to do its job, there is a question as to what it is there for."

She said the Lords "should be free to scrutinise and to question and to hold the government to account and to send back legislation it feels is not adequate, either in terms of its clarity or because it infringes the individual liberties we all hold dear".

"There's going to be lively debate about this in the House of Lords and I think there will be a lot of views expressed."

Image caption Lord Strathclyde said there were no plans to change the House of Lords' powers

But Lord Strathclyde told Sunday Politics said there was "absolutely no suggestion" the House of Lords' powers would "fundamentally change".

He said: "I made the most mild and humble recommendation about the smallest part of the legislative process on secondary legislation, where frankly most of us had understood that the customs, practice and conventions that had been built over the course of the last 50 years would stick.

"Last October they broke down, as a result of which there is no consensus and no agreement on what those powers should be, which is why I propose not so much a diminution of the powers of the House of Lords but a new power to reject and ask the House of Commons to think again."

'Blocking tactics'

Lord Strathclyde added the Conservative government had faced "blocking tactics, using vetoes, rather than working with the House of Commons and the government to try to improve that legislation".

Baroness D'Souza also said she would be pushing for a motion on the issue of reducing the size of the Lords, saying it should not be larger than the House of Commons, and suggesting the number of peers be cut to around 500 from its current 807.

She said she believed at least 20% of peers in the house should be independents or cross-benchers and no one party should have a political majority, adding these changes could be implemented by 2020.

The current size of the House was so large, it was starting to have an impact on the ability of the House of Lords to hold the government to account, the Lord Speaker added.

Sunday Politics will be broadcast on BBC One at 11:00 BST.