A major overhaul of the oversight of Britain's intelligence agencies, which could lead to an opposition politician chairing parliament's intelligence and security committee and reform of the intelligence commissioners, needs to be introduced, Ed Miliband has said.

The Labour leader praised Barack Obama for starting an "important debate" in the US – after the White House appointed a panel in the wake of the Edward Snowden leaks – and called for a similar debate in Britain.

In some of his most extensive comments on the NSA leaks, Miliband told a Guardian audience that reforming the oversight of GCHQ, MI5 and MI6 was "definitely" part of his campaign to challenge "unaccountable power".

This was the main theme of his Hugo Young lecture at Kings Place, home to the Guardian, in which Miliband announced that a Labour government would give patients a formal role overseeing changes to local NHS services.

Unveiling a significant reconfiguration of public services, designed to "tackle inequalities of power at source", Miliband said that Labour would force clinical commissioning groups to appoint patients to committees overseeing major changes to local NHS services. Patients could be nominated by local healthwatch bodies or they could be nominated by a cancer charity if the changes affected local cancer services.

Miliband said: "We need to find far better ways of hearing the patient voice. So a Labour government will ensure that patients are involved right at the outset: understanding why change might be needed, what the options are and making sure everyone round the table knows what patients care about. No change could be proposed by a clinical commissioning group without patient representatives being involved in drawing up the plan."

The proposals by Miliband, who also announced that parents would be given a new power to call in a specialist team to improve the performance of failing schools, are the key elements of his plans to devolve power in public services. Amid criticism that he has neglected public services, as he focuses on challenging the energy giants and other large businesses, Miliband said he was bringing the same approach – tackling unaccountable power.

He said: "Everyone – not just those at the top – should have the chance to shape their own lives. I meet as many people frustrated by the unresponsive state as the untamed market: the housing case not dealt with, the special educational needs situation unresolved, the problems on the estate unaddressed.

"And the causes of the frustrations are often the same in the private and public sector: unaccountable power with the individual left powerless to act against it. So just as it is One Nation Labour's cause to tackle unaccountable power in the private sector, so too in the public sector."

Miliband made clear that his challenge to "unaccountable power" would include Britain's intelligence agencies as he said that reform should focus on two areas. These are parliament's all party intelligence and security committee, which is always chaired by a senior MP from the governing party, and the commissioners who oversee the intelligence agencies.

The Labour leader said: "I already believe, and this is what my Labour colleagues have been saying, that there are clearly changes that are going to need to be made in relation to the intelligence and security committee and the oversight it provides.

"That is everything from the resources they have at their disposal, who chairs the committee and whether it should be somebody from the government party or the opposition party, their power to compel witnesses – a range of issues.

Labour leader Ed Miliband put challenging 'unaccountable power' at the heart of his Hugo Young lecture. Photograph: Anthony Devlin/PA

"There is also a set of issues around the commissioners – the intercept commissioner and the intelligence commissioners – and the framework for that. This is an issue Labour is looking at and we will have more to say about it in the coming months. President Obama has started an important debate in the US and that is a debate that needs to take place here too."

Making clear that these reforms were wholly within the context of his Hugo Young lecture, he said: "The issue of oversight of the intelligence services and the way they work is definitely part of this agenda. My commitment is that we do need to look at these issues, they are important."

But Miliband said he was supportive of the work of the intelligence agencies and said that the ministerial oversight, which means that the relevant secretary of state has to approve any interception, was a good system. He said: "My starting point in this is the intelligence services do an important job. As somebody who wants to be the prime minister of this country I know that they do an important job in seeking to keep us safe.

"What has got to be done in relation to that is that there have got to be the right checks and balances in the system because the guarantee that we need for the British people is that the services are keeping us safe and in doing so are subjected to proper oversight. There are definitely issues of oversight that need to be looked at in this country.

"There are two reviews, as I understand it, going on – one by the intercept commissioner and one by the intelligence and security committee. That is important. We need to look at what they come up with."

On the ministerial oversight of interception, he said: "It is worth saying also that there is in this country … ministerial sign off when intercept and so on takes place. That is a very, very important safeguard. I do believe the intelligence services do important work. But I absolutely endorse the idea that there are important issues of liberty and liberty is an important part of Labour's agenda."

The Labour leader paid tribute to Young, the Guardian's late political commentator, who wrote a landmark biography of Margaret Thatcher entitled One of Us. Miliband said that the late prime minister's famous phrase provided an important lesson on the need for a leader to have a clear sense of direction.

"The very fact that Lady Thatcher was able to ask that question ['Are you one of us?'] meant that she was absolutely clear what she stood for. Prime ministers are elected on a manifesto and make policy on that basis. But in my view, whether they achieve lasting change depends not just on specific policies, but whether they can define the purpose and mission of their government."

In his remarks on public service reform, Miliband also said that a future Labour government would consider overturning an amendment to the care bill that would make it easier for administrators who take over failing NHS trusts to change services in their local area.

Jeremy Hunt, the health secretary, introduced the change after judges rejected his attempt to overturn an earlier ruling that he lacked the power to implement cuts to the A&E and maternity departments at Lewisham hospital in south-east London.

Miliband also answered critics who accuse Labour of failing to acknowledge that public services will have to survive on tighter budgets after Ed Balls pledged to run a current budget surplus by the end of the next parliament. He said: "Clearly the next Labour government will face massive fiscal challenges. Including having to cut spending. That is why it is all the more necessary to get every pound of value out of services. And show we can do more with less. Including by doing things in a new way."