United Airlines has strengthened its alcohol policy for pilots -- a week after two of them were arrested for allegedly being under the influence before a flight from Scotland to Newark.

The airline now requires that pilots refrain from drinking alcohol at least 12 hours before reporting for duty -- up from the eight hours mandated by the Federal Aviation Administration, USA Today reported.

The FAA's rule on a pilot's blood-alcohol content before entering the cockpit -- 0.04 percent -- has not changed under the airline's new policy, which went into effect Saturday.

Pilots were notified of the policy change in a bulletin from Henry Canada, the manager of flight operations, according to the news outlet.

"It is essential that pilots understand that minimal compliance of United's policy does not assure compliance with DOT (U.S. Department of Transportation) or individual state standards," the bulletin says.

"Countries outside the United States have differing policies which include a blood alcohol content of 0.00% and punishment criteria," it added. "It is the sole personal responsibility of the pilot to report for duty as defined by the company, DOT/FAA or the governing country."

The carrier did not mention the Scotland incident in a memo about the new policy.

On Aug. 3, United Flight 162 was canceled after the pilots failed a breath test before takeoff.

Capt. Glendon Gulliver, 61, has been charged in a Scotland court with being over the legal limit, according to Fox News. The 45-year-old first officer had not been charged as of Tuesday.

According to the FAA's guidelines, pilots must wait a minimum of eight hours before duty, though "a more conservative approach is to wait 24 hours from the last use of alcohol before flying."

However, the agency also warns pilots to consider the effects of a hangover and to "use good judgment."

United's move also follows another incident involving an allegedly drunken flight crew member.

A flight attendant on a United Express flight from Chicago to South Bend, Indiana, was charged with public intoxication in the Aug. 2 incident and was fired. The flight was operated by United affiliate Air Wisconsin.

Flight attendants also are required not to drink alcohol for a minimum of eight hours before they report for duty.

United did not immediately respond to The Post about whether the new guidelines also apply to the cabin crew, as well as the flight status of the two pilots arrested in Scotland.