The Kulluk is pictured at left

(CBS News) CBS News has learned that the U.S. Coast Guard has launched a criminal investigation into the activities of a 572-foot oil drilling and exploration ship run by the Noble corporation, the same company that owns the Kulluk drilling rig that ran aground in rough Alaskan seas on Monday. Noble is contracted by Royal Dutch Shell to search for oil in the Arctic.

The revelation that another Noble ship working for Shell may have been operating with serious safety and pollution control problems bolstered allegations from environmental activists that the oil industry is unable to conduct safe oil drilling operations in the Arctic Ocean.

The Coast Guard conducted a routine marine safety inspection when Noble's Discoverer arrived at a Seward, Alaska port in late November. The inspection team found serious issues with the ship's safety management system and pollution control systems. The inspectors also listed more than a dozen "discrepancies" which, sources tell CBS News, led them to call in the Coast Guard Investigative Service (CGIS) to determine if there were violations of federal law.

Sources told CBS News that when criminal investigators arrived, the Noble Discoverer's crew had been provided with lawyers and declined to be interviewed.

After the Coast Guard's initial inspection of the Noble Discoverer, on Nov. 30, Capt. Paul Mehler, the Officer in Charge of Marine Inspection in Western Alaska issued a Port State Control Detention for the Noble Discoverer, effectively grounding the ship until safety violations were fixed. By Dec. 19, the ship was released from Port Detention but still remains in Seward for additional repairs.

According to the Coast Guard, the recent issues come after a string of warning signs pointing to potential issues on the Discoverer and the Kulluk over the course of 2012. An "enforcement warning" for being a "pollution source" was issued to the Noble Discoverer in Anchorage, on Sept. 24, following an investigation into an oil discharge. On May 21, in Seattle, days before the ship sailed toward the Arctic Ocean, an inspection of the Discoverer found 23 deficiencies, including problems with bilge water management system, ventilation, electric system, and ship's engine.

The Kulluk has also had recent violations, including three enforcement warnings for being a source of pollution in 2012 and a Coast Guard inspection last May that found 19 deficiencies in electrical and maintenance systems. Officials say there is no sign that the grounded Kulluk, which is carrying 143,000 gallons of diesel, is leaking fuel.

Activists from Earthjustice, an non-profit environmental law firm that is suing Shell, claim the safety record of the entire fleet deployed for Shell in the Arctic raises questions about whether the ships and rigs are capable of handling conditions in the rough Arctic Ocean.

"No matter how many times we hear Big Oil tell us that everything is under control, the fact is the oil industry cannot operate safely and responsibly in the Arctic Ocean, and the risks of more reckless oil drilling are too great for us and future generations," Earthjustice president Trip Van Noppen said in a statement.