NEW YORK -- The NFL and the officials' union were talking again.
Two people familiar with the talks say that the NFL and the locked out officials' union met Sunday.
It was uncertain whether progress was made in an attempt to reach a new collective bargaining agreement, or when further negotiations would take place.
The two people spoke to The Associated Press on the condition of anonymity because the talks are not being made public.
The NFL locked out the officials in June after their contract expired. The league has been using replacement officials, and through three weeks of the regular season there has been much criticism over the way some games are being handled.
Earlier Sunday, the NFL players' union sent an open letter to team owners calling for an end to the lockout.
On Sunday, there were more suspect calls during several games.
Replacement officials admitted making two mistakes in Minnesota's victory over San Francisco, while a few other games included questionable calls that could have affected the outcomes.
Referee Ken Roan said he twice granted 49ers coach Jim Harbaugh video challenges after Harbaugh called timeout in the fourth quarter. Neither challenge should have been allowed once Harbaugh asked for time.
"What I told him was, 'Well you challenged it not knowing what the result of the play was going to be,"' Roan said. "So I granted him the challenge and we went and looked at it. That was wrong. I should not have."
Both mistakes happened in the span of six plays in Minnesota's 24-13 upset of the 49ers.
"My interpretation of it was that he could do that based upon the time factors and not knowing it was a challengeable play to begin with when he called timeout," Roan said. "If you don't have a timeout to lose, you can't make a challenge."
The sides also met last week for two days, but the negotiations remained far apart. Also, the league last week warned teams that it won't tolerate confrontational behaviour toward the new officials.
Negotiations with the NFL Referees Association broke down several times during the summer, including just before the season. This is the first time the league is using replacements since 2001.