The talks over the proposed Transatlantic Free Trade Agreement are set to run until Friday during which time representatives will discuss public services, investments, energy, raw materials and regulation issues.
The five-week delay in the talks was initially caused by the battle in the US Congress over the budget and health reform which led to a government shutdown.
In the meantime the National Security Agency (NSA) was accused of tapping Merkel’s phone leading to increased tension between Germany and the US and calls from some quarters to delay or cancel the talks.
But the EU Commission said on Monday its trade representative Ignacio Garcia Bercero welcomed his US counterpart Dan Mullaney to restart the negotiations.
The agreement would create the world's biggest free trade zone, home to over 800 million people. According to one estimation it would create 160,000 jobs in Germany.
The talks began in the summer and experts believe a deal could create two million new jobs. But an agreement is unlikely to come before late 2014 at the earliest.
Environmentalists have warned a deal between the EU and US would lead to a weakening of environmental regulations in Europe.