Previously, CNOOC just "anticipated noise in Washington" and a maximum 90-day government review process, but "never expected it would become as strident as it has become," the source said.

Last week, Congress introduced legislation that would delay the process as CNOOC battles with bid rival Chevron.

The comments came as a Japanese evening daily newspaper reported that CNOOC had thrown in the towel, but a CNOOC spokesman said the $67 a share bid was still on the table.

The