By Gene Cherry

RALEIGH, North Carolina (Reuters) - NFL owners and players completed two days of talks on Wednesday as they sought common ground for a new collective bargaining agreement to end a lockout now in its 13th week.

A joint statement confirmed only that the two sides held discussions under the auspices of federal Chief Magistrate Judge Arthur Boylan and that talks would continue, likely next week.

"At the request of Judge Boylan, both sides have agreed to maintain the confidentiality of the substance of the talks," the statement said.

It marked the third group of meetings in two weeks as the two parties attempted to resolve a biter dispute that is threatening the 2011 season for American's most popular professional sport.

Commissioner Roger Goodell and owners Jerry Richardson (Carolina), Clark Hunt (Kansas City), Robert Kraft (New England), John Mara (New York Giants) and Dean Spanos (San Diego) led the league delegation at the latest meetings in Maryland.

NFL Players Association executive director DeMaurice Smith and president Kevin Mawae also were present, along with players Domonique Foxworth, Tony Richardson, Jeff Saturday and Brian Waters.

The 32 league owners are scheduled to meet in Chicago for an update on the progress of the talks.

The two sides are seeking ways to divide more than $9 million in annual league revenue.

The owners want to increase their share to ensure they can meet operational expenses and construct new facilities.

The players claim the owners have failed to provide enough financial evidence to prove they needed a bigger slice.

If the league is to have a full preseason and a complete regular season, an agreement is needed soon.

Some owners have hinted that a deal would be needed by July 4 for a full schedule of activities and Labor lawyer John Hancock agreed.

"They should have a deal by July 4th," he said in an email to Reuters on Wednesday.

"They have played all their games with the court and I believe they are finally bargaining because neither side wants to see the season scrapped and neither side has a life or death issue that would warrant a strike or a lockout."

Others said there could be financial sticking points that might delay an agreement.

Both the U.S. District Court in Minnesota and the Eighth U.S. Circuit of Appeals in St. Louis have issued rulings in the case since bargaining talks broke down and the players association decertified itself as a union on March 11.

Nine players including high profile quarterback Tom Brady then filed a class action antitrust lawsuit against the league and NFL owners on March 12 locked out the players.

The players sought an injunction against the lockout, which a Minnesota federal judge granted. But a panel of the Eighth Circuit twice has ruled against the lower court with a final decision pending.

Meanwhile, the lockout continues and time draws nearer for the traditional opening of league training camps in late July.

If there is no agreement by September, when the regular season starts, revenue losses could reach $1 billion, according to estimates.

(Editing by Julian Linden)