Iran's oil exports have picked up modestly in January for the third consecutive month, according to sources who track tanker movements, adding to signs that the easing of sanctions pressure on Tehran is helping its oil exports to recover.

The increase in shipments is around 50,000 barrels per day (bpd), according to one tracker company, which would take Iranian exports to around 1.2 million bpd for January and add about $150 million a month to Tehran's depleted oil revenues.