Secret document suggests US spies could eavesdrop on top allies' citizens

The US National Security Agency is authorised to spy on the citizens of the nation's closest allies, including Britain, even though those English-speaking countries have long had an official non-spying pact, according to a newly disclosed document.

The classified NSA paper, which appears to be a draft and dated January 2005, states that under specific circumstances, the United States intelligence agency may spy on citizens of Britain without that country's consent or knowledge. The memo, provided by former NSA contractor Edward Snowden, is labelled secret and "NOFORN", indicating it may not be shared with any foreign country.

In recent months, the NSA's activities have stoked anger after leaked documents have exposed US spying on political and economic partners including Germany and France, as well as foreign leaders. But until now, there has been almost nothing disclosed about spying among the "five eyes" countries - the US and its close intelligence partners Britain, Canada, Australia and New Zealand.

The NSA did not respond to questions on whether the draft became policy and whether spying on Britain without its consent had ever taken place.

But portions of the document appear to indicate that, whether by formal agreement or simply longstanding practice, both Britain and the US believed that in extraordinary circumstances, one country might feel compelled to spy on citizens of the other.

In a reference to an intelligence-sharing compact struck in March 1946, the memo said the two nations had agreed "that both governments will not target each other's citizens/persons".