union representing about 35,000 striking Verizon Communications Inc workers filed unfair labor practice charges against the telephone company, complaining that it "refused to bargain in good faith."

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 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.

The remaining 10,000 striking workers are represented by the International Brotherhood of Electrical Workers.