With the flames still burning on one of the two supertankers that colided off the coast of Tobaco on July 19, the Mobil Oil Co. has sued the owners of both ships for $50 million for losses in its cargo of 2 million barrels of crude oil.

The suits were filed in federal court in New York

In one suit, Mobil alleged that the Aegean Captain -- the ship that was not carrying Mobil's cargo -- caused the accident because those in charge of the ship were "incompetent and inattentive to their duty."

"the vessel failed to a safe speed, given the state of visibility, the maneuverability of the vessel, and efficiency and limitations of its radar equipment and the traffic in the area," Mobil charged, adding that the defendants permitted the Aegean Captain "to sail in unseaworthy condition."

Accused in that suit were the Quadrant Shipping Corp. of Monrovia, Liberia, owner of the ship and operator of the vessel.

The other suit is against the owner and operator of the Atlantic Empress, the tanker carrying Mobil's cargo. They are respectively the Branco Shipping Co., Ltd. of Liberia and Sun Enterprises, Ltd. of Pireaus, Greece. The owners of both ships have New York City offices.

In the second suit, Mobil merely alleges that the accident resulting in Mobil's cargo loss "was not caused by any fault or breach of cantract on the part of [Mobil]. . . but rather was caused by the negligence and breach of contract" by Branco as well as "negligence and lack of care" on the part of Sun. Mobil charged, for example, that Sun failed "to properly man and make the vessel on all respects seaworthy." Twenty-six crew members of the Atlantic Empress were lost and presumed killed in the collision.

Mobil's shipment on the Atlantic Empress was coming from the Persian Gulf and destined for Beaumont, Tex. There remains some mystery as to who owned the 1.5 million barrels of oil aboard the Aegean Captain, which apparently was making a curious trip from way of the Netherlands Antilles.

Mobil attorney Louis Scheinbaum said in an interciew that it was "not at all unusual" for a company to file suit against both ships in such an accident because the "grounds for recovery are different for the carrier as opposed to the non-carrier. He said both ships could be found to have been negligent.