Verizon Communications Inc
The move came on the sixth day of a strike involving about 45,000 Verizon technical and customer service workers who walked out after their labor contract expired and talks between the company and the unions failed.
The Communications Workers of America filed unfair labor practice charges against the telephone company, complaining that it refused to bargain in good faith.
Verizon filed complaints against the CWA and the International Brotherhood of Electrical Workers, which represents about 10,000 of the striking workers. Verizon said the unions were not bargaining in good faith.
The CWA said on Friday that it asked the National Labor Relations Board (NLRB) to order Verizon management to negotiate in good faith. It filed complaints in the New York and Baltimore offices of the NLRB.
Verizon filed its complaints with the NLRB in New Jersey and in New York.
Despite the complaints both sides said they expected talks to continue into the weekend.
The strikers are technical workers and customer service representatives for Verizon's U.S. northeast and mid-Atlantic wireline unit, which provides telephone and high-speed Internet services for homes and businesses as well as Verizon's FiOS television services.
Verizon is looking to cut costs in its wireline business, which has been declining for years as customers get rid of home phones in favor of cellphones and Internet services.
But the unions say the company is asking for too many concessions in areas such as healthcare contributions, pensions, sick days and other work rules.
(Reporting by Sinead Carew. Editing by Robert MacMillan and Carol Bishopric)