RIO DE JANEIRO (AFP) - Chevron was given the green light to resume oil exploration in Brazil on Monday following a massive 2011 spill which led to the US oil giant halting its activities.

The National Petroleum Agency (ANP) said it had approved Chevron's plan to resume production in four wells of the Frade oil field, located some 370km north-west of Rio, for a period of 12 months.

ANP said it would keep Chevron activities under constant surveillance.

In November 2011, some 3,000 barrels of crude spilled into deep Atlantic waters in the Frade field and Chevron admitted responsiblity for the disaster.

As a precaution, Chevron voluntarily interrupted its Brazilian activities in March last year, after detecting another leak three kilometres from the first.

Last August, a Brazilian court ordered Chevron and its driller Transocean to stop their oil drilling and shipping activities within 30 days.