Barack Obama has unveiled measures he says will increase transparency and build public trust in controversial US spying programmes - but there are no plans to stop collecting information.

"Given the history of abuse by governments, it's right to ask questions about surveillance, particularly as technology is reshaping every aspect of our lives," the US president said on Friday.

He said that his administration would work with Congress to reform the Patriot Act and provide greater oversight and transparency. The reforms would target section 215 of the act, which allows the National Security Agency to collect data from millions of communications without a warrant.

He added that he planned to create an "adversary" position that would raise civil liberties concerns on cases which went to the secret Fisa court, which governs programmes run by the National Security Agency.

The court currently hears only from Justice Department officials who want the surveillance approved.

I want to make clear once again that America is not interested in spying on ordinary people. US President Barack Obama

"All these steps are designed to ensure that the American people can trust that our efforts are in line with our interests and our values," Obama said.

"And to others around the world I want to make clear once again that America is not interested in spying on ordinary people."

However, there was no intention to stop current spying programmes revealed by whistleblower Edward Snowden which collect data from millions of internet and telephone conversations by foreigners and American citizens.

Obama said that Snowden, who has been granted asylum in Russia, was not a patriot but admitted that his disclosures prompted a faster and more passionate response than if Obama had just appointed a board to review the policies.

Obama added that Snowden's asylum status was not the only factor in a worsening of relations between the US and Russia. The president recently cancelled a meeting with his Russian counterpart, Vladimir Putin.

Since the data-gathering programmes were revealed in June, Obama has repeatedly said he would encourage a national conversation about balancing the need for US surveillance with people's rights to privacy.

On July 25 the House of Representatives rejected a bid to cut funding for some NSA programmes by a surprisingly narrow 205-217 vote, with both conservatives and liberals worried about citizens' privacy.

Obama's reform plans came after he held a meeting on Thursday with representatives of civil liberties groups and executives from technology companies including AT&T, Apple and Google. The meeting was not on Obama's public schedule.