LONDON — BP has returned to profit in the third quarter as it recovers from the impact of April's Gulf of Mexico oil spill, but says it still cannot estimate the full cost of the disaster.

The oil company today reported a net profit of $1.79 billion, compared with a loss of $17.2 billion in the second quarter but still below a profit of $5.34 billion a year earlier.

Replacement cost profit — a key industry benchmark — was $1.85 billion, way below analysts' forecasts of around $4.5 billion. The third quarter figure released compared to a loss of $17 billion in the second quarter and a profit of $7.36 billion in the comparable period a year ago.

Earnings were dented by a pretax charge of $7.7 billion related to the Gulf of Mexico spill, bringing the total charges this year to $39.9 billion.