The British Petroleum said Monday it has spent two billion U.S. dollars in costs related to the Gulf of Mexico oil spill.

The British oil giant said in a statement issued in Houston?that the costs included those of spill response, containment, relief well drilling, grants to the Gulf states, claims paid to affected individuals and businesses, and federal costs.

"It is too early to quantify other potential costs and liabilities associated with the incident," said the company, whose Deepwater Horizon drilling rig exploded off the Louisiana coast in April and triggered the worst oil spill in the U.S. history.

The BP last week agreed to set up a-20 billion-dollar fund to compensate victims of the spill.

In Monday's statement, the company also updated some of its response operations including operations to skim oil from the surface of the Gulf that have recovered in total about 558,000 barrels of oily liquid.

Apart from the two oil containment systems currently in operation, the BP said it is continuing preparations for the next step in containment operations.

"Construction of the first floating riser remains on schedule for the end of June," it said.

A vessel will be connected to that riser and it is expected that this system will be available to begin first operations around the end of June or early July, said the statement.