In the eight months since Kenneth R. Feinberg took over the $20 billion fund to compensate victims of the Gulf of Mexico oil spill, he has been attacked by many of those filing claims and by coastal state politicians who argue that the process is opaque, arbitrary and slow. Many of them have also argued that Mr. Feinberg’s recently published estimates of future damage to those in the gulf are too optimistic, and thus his offer of compensation in a final settlement is too low.

Now he is getting complaints from another quarter: BP.

The oil giant is arguing that if anything, Mr. Feinberg’s proposed settlements are too generous. The planned payments far exceed the extent of likely future damages because they overstate the potential for future losses, the company insists in a strongly worded 24-page document that was posted on the fund’s Web site Thursday morning.

Basing its estimates on much of the same data Mr. Feinberg used, the company concluded that there was “no credible support for adopting an artificially high future loss factor based purely on the inherent degree of uncertainty in predicting the future and on the mere possibility that future harm might occur.”

Mr. Feinberg released the rules that will govern final settlements this month. In general, the program announced, settlements paid out by the fund would be double the 2010 losses for most of those filing claims, less any money previously paid by the fund.