The leaders of Germany, France, Italy and the United Nations were all targets of spying by the US intelligence service, according to the latest revelations by whistleblowing website WikiLeaks.
According to WikiLeaks, the US National Security Agency (NSA) allegedly listened in on telephone conversations between Chancellor Angela Merkel and the United Nations Secretary-General Ban Ki-moon in 2008.
It also revealed details from a 2011 meeting between Merkel, former French president Nicolas Sarkozy and Italy's ex-premier Silvio Berlusconi.
In a call allegedly intercepted by the NSA, Ban complimented Merkel on her efforts to fight climate change and bring other EU leaders on board.
Ban reportedly said that without continued leadership on the issue from the European Union, it would be hard for the UN to make a commitment at a then-upcoming conference in Poznan, Poland.
The UN leader also expressed optimism that the recent election of Barack Obama as US president presented an opportunity to get the United States more closely involved in climate change negotiations.
German media reported last year that the NSA listened in to the chancellor's office for decades, including on Merkel's predecessors, citing WikiLeaks documents.
The recent leak was also reported by the same three media outlets: the newspaper Sueddeutsche Zeitung and broadcasters NDR and WDR.
"Today we showed that UN Secretary-General Ban Ki Moon's private meetings over how to save the planet from climate change were bugged by a country intent on protecting its largest oil companies," WikiLeaks founder and editor Julian Assange said.
"It will be interesting to see the UN's reaction, because if the Secretary-General can be targeted without consequence, then everyone, from world leaders to street sweepers, is at risk," he said.
Other documents made available by WikiLeaks mention secret agreements between Japanese and European trade representatives, diplomatic tensions between Israel and the US, as well as a three-way meeting between Merkel, Sarkozy and Berlusconi.
In October 2011, Merkel and Sarkozy are said to have put pressure on Berlusconi over his country's debts. The tone of the conversation had been "very harsh toward the Rome government," according to WikiLeaks.
The document appears to be based on comments made by Berlusconi's foreign policy advisor Valentino Valentini. Sarkozy is reported as warning Berlusconi that his country's financial institutions "could soon 'pop' like the cork in a champagne bottle."
According to WikiLeaks, the NSA also tapped the phone of leading figures at the World Trade Organization and the UN High Commissioner for Refugees.