WASHINGTON -- American Telephone and Telegraph Co., the largest U.S. long distance company, has asked for another rate increase that could affect the cost of calling to and from the United States.


The latest request seeks an average 5 percent boost for "USA Direct" service to 27 countries, which enables AT&T customers traveling or living abroad to bypass foreign telephone companies and get connected by an AT&T operator in the United States.


In addition, direct-dial calls from the United States to some countries would increase 1.3 percent but decrease to most countries. The countries were not named, but AT&T said the changes would "better align prices with the costs of providing the services.''


Charges for using domestic telephone credit cards or operator service would rise 3.8 percent, AT&T said.


Two weeks ago AT&T received federal permission to boost prices of domestic long-distance calls that it said would average about 35 cents per customer per month and generate $274 million a year in additional revenue.


The new proposal submitted Wednesday to the Federal Communications Commission should bring it another $259 million a year if it goes into effect Jan. 10 as planned, the company said. AT&T spokesman Jim McGann said inflation and increased costs for providing the services prompted the request for higher rates.


Regional U.S. phone companies seeking authority to provide long-distance service said it underscores the need for more competition in the $60 billion-a-year industry.


AT&T said it charges an average of 15.9 cents a minute for domestic calls directly dialed from private telephones, and pledged no rises in 1995.


Unlike in European and some Asian countries, U.S. phone companies generally charge for full minutes. Card-reading public telephones that accept stored-value debit cards are not yet in general use.