TOKYO (Reuters) - Nippon Steel ( NISTF ) Vice Chairman Takahiro Mori said on Tuesday the Japanese company remains committed to talks with the United Steelworkers (USW) over its bid to acquire U.S. Steel.

Mori, the key negotiator of the $14.9 billion buyout deal, said USW President David McCall "has not seriously considered any of the proposals that we have presented" in a letter to the U.S. Steel employees.

"We just need USW leadership to come to the table. I am hopeful they will do so in the very near future," Mori wrote.