At Amnesty International we were appalled at last week's news that the UK government has been spying on our communications. This week, we are demanding answers. On Friday, we wrote to Prime Minister David Cameron to ask for an explanation why the UK government is spying on a human rights organisation.

This follows the first official acknowledgement last Wednesday of what many of us had long suspected: the British government is spying on Amnesty International's communications. But what we still don't know is almost more shocking. We don't know which communications were accessed, or why, or how many times, and we don't know whether this surveillance is ongoing.

And unless Cameron decides otherwise, we are unlikely to find out the answers to these questions any time soon. The Investigatory Powers Tribunal (IPT), the body that oversees UK intelligence agencies, holds most of its hearings in secret. The only reason we know the little bit we do is because the government agencies breached their own internal guidelines on how long they could store our communications.

In fact, the original judgment of the IPT found no such violation, and we were only notified by email 10 days later that this was an error. The tribunal had accidentally mixed up Amnesty International with another organisation.

Better oversight needed

This clearly underscores why more and better oversight of surveillance programmes is so sorely needed. This is especially true when you consider how long we have been trying to get some confirmation from the US and UK governments as to whether they are reading our communications.

In 2008, Amnesty International USA was party to a case seeking to challenge the US government intercepting their communications. In 2013 the US Supreme Court rejected the case, holding that Amnesty International USA "lacked standing" because the risk of surveillance was too "speculative".

In other words, we had to be able to prove details about programmes the government kept secret before we could get in the courthouse door.

The British prime minister has also - echoing comments made by the FBI in the US - attacked encryption as a hindrance to law enforcement.

But that was before the Snowden disclosures revealed the extent of mass surveillance by the US and the governments it shares data gleaned through surveillance with, known as the "Five Eyes" alliance. Now we know more.

We know that these agencies have spied on millions of people around the world and have spied on politicians, journalists and organisations like Doctors of the World, UNICEF, the South African Legal Resources Centre, and now Amnesty.

Human rights defenders, activists and investigative journalists around the world risk their lives daily to uncover abuses and corruption, and face threats to their safety from governments, armed groups and criminals for doing so. When they cannot know who is accessing their information, or who they might be sharing it with, their work becomes impossible.

Encryption as hindrance?

Yet despite all we now know, not that much has changed, the response of many governments is still to resist greater transparency, call for yet more surveillance, and urge crackdowns on tools such as encryption, essential for human rights groups to help protect information about human rights violations from the eyes of governments committing them.

The British prime minister has also - echoing comments made by the FBI in the US - attacked encryption as a hindrance to law enforcement. Weakening encryption by attempting to insert "backdoors" for law enforcement could undermine not only the work of human rights activists, but could undermine the security of internet users everywhere.

This is among the reasons why the United Nations Special Rapporteur of Freedom of Expression, David Kaye, called on states to "promote strong encryption and anonymity" online in a report to the Human Rights Council this June.

The UK's independent reviewer of terrorism legislation, David Anderson, has called for a new, clearer law to govern surveillance that would require security agencies seek judicial authorisation to get warrants to intercept communications.

His report warned that the law governing surveillance has been "patched up so many times as to make it incomprehensible to all but a tiny band of initiates".

Despite this and other evidence of abuses under the existing law, David Cameron has resisted reforms such as judicial warrants for surveillance, and any new legislation in this area is expected to expand, rather than reduce, surveillance powers.

More and more states are seeking to expand their surveillance powers, from France, to Pakistan, to Switzerland.

The global trend to expand unaccountable surveillance systems must be resisted. More and more states are seeking to expand their surveillance powers, from France, to Pakistan, to Switzerland.

Informed public debate

Since the Snowden revelations, there has been some cause for hope. The US recently ended the indiscriminate bulk collection of US phone calls with the USA Freedom Act. Only a first step, it shows that reform is possible once information is available on which to base an informed public debate.

In the UK, it is clear that the time has come for radical reform of the surveillance system. We can no longer allow for a secret and unaccountable system that spies on human rights organisations and others without safeguards like meaningful judicial scrutiny.

Despite the revelations last week, the UK government still has many questions to answer. Again, why was the government spying on Amnesty International? Are they still doing so? Who have they shared our information with? Who else are they spying on?

Today Amnesty International is asking Cameron to urgently launch an independent inquiry to answer these questions.

Joshua Franco is advisor on technology and human rights working on Amnesty International's #UnfollowMe anti-surveillance campaign.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.