The U.S. Department of Justice is considering seeking to block AT&T Inc.'s merger with Time Warner Inc. as it continues talks with the two companies, the Wall Street Journal reported on Thursday.

The financial newspaper also said the DOJ might still consider approving the deal with certain conditions but that the two sides were not close to an agreement.

Shares of Time Warner were down 4.2 percent at $94.2, while AT&T's shares inched up.

The U.S. wireless carrier is in the process of buying Time Warner for $85.4 billion in a deal that is expected to close by the end of the year.

Neither company had any immediate comment.