Major League Soccer has ordered Orlando City to cease pursuit of AC Milan’s Antonio Nocerino because D.C. United has exclusive league rights to negotiate with the Italian midfielder, the Insider has learned from multiple sources.

United last month filed a discovery claim, a mechanism preventing other MLS teams from contacting the player or engaging in negotiations.

General Manager Dave Kasper and managing general partner Jason Levien met with Nocerino in Milan last week. Initial reports suggested Nocerino probably would not end up signing with United. However, the club has remained in contact with the player’s representatives and, according to one source, was encouraged by recent discussions.

Orlando City’s interest, which came to light in recent days, stemmed from Nocerino’s friendship with former Milan teammate Kaka, the Florida club’s star attraction. Italian media outlets claimed Nocerino had chosen Orlando over United. On Monday, the Orlando Sentinel reported the team was, indeed, actively pursuing Nocerino.

Without acquiring the discovery rights from United, however, Orlando would be in violation of tampering rules.

United officials declined comment, but one source familiar with the drama said they were “irate” with Orlando and that the “meddling” had disrupted negotiations and provided the player’s agent with additional bargaining leverage.

“There have been no tampering charges filed at the league office, so we will not comment on any hypothetical situations,” an MLS spokeswoman said.

A source said United has not ruled out filing a tampering complaint.

Orlando City, which is entering its second season in MLS, did not reply to a request for comment.

Last summer, MLS fined Orlando City and its coach, Adrian Heath, for violating the tampering policy. Heath had said publicly that he would attempt to sign Sporting Kansas City forward Dom Dwyer.

To sign a player through the discovery process, a club must first place the player on a discovery list. A club may have up to seven unsigned players on the list and may remove or add players at any time. The lists are not made public or shared with other clubs.

If one or more clubs try to add the same player to their discovery list, the club that filed the initial claim will gain the right to negotiate with the player. Even if negotiations fail, the club would retain the right of first refusal in the event the player signs with the league.

Teams are allowed to acquire discovery rights to a specific player from another club. The price: $50,000 in allocation money. The initial rights holder would then have to accept that offer or make a “genuine, objectively reasonable offer” to the player in order to move along the process. While negotiations with Nocerino continued — and an offer was tendered — United apparently declined Orlando’s overtures.

There are many cases each year in which clubs are unaware of discovery claims made by competitors. In this case, however, United’s engagement with Nocerino was well known in MLS and international circles.

MLS — which owns all teams and awards operating rights to league investors — created the discovery rule to prevent clubs from competing for specific players. The only situation in which teams directly compete for players is internal free agency, which was enacted for the first time this offseason. (Ten players signed with new teams.)

Around the world, clubs from the same leagues engage in furious struggles for players every winter and summer.

MLS’s discovery rule came to the forefront last summer when Chelsea legend Didier Drogba decided to join the league. The Chicago Fire owned his discovery rights, but the Ivorian striker preferred to play for the Montreal Impact. The sides resolved the matter through a sign-and-trade agreement: Chicago acquired Drogba, then traded him to Montreal for considerable amounts of allocation money.

United sees Nocerino, 30, as one of the final pieces to its preseason roster puzzle. The club acquired wingers Lamar Neagle and Patrick Nyarko early in the offseason and traded for central midfielder Marcelo Sarvas on Monday. United is also in contact with several other players abroad to both further bolster the squad and provide additional options in case the Nocerino plan falls through.

Kasper was scheduled to visit players in Greece, France and England this week.

A resolution in the Nocerino matter is expected soon. His options are narrower because transfer windows in most countries have closed. MLS’s window is open until mid-May, however. If he does not join D.C. or Orlando, Nocerino would probably remain with Milan through the end of the Serie A season in May.

The former Italian national team player was loaned to Torino and Parma last season and has appeared in only two league matches for Milan this season. He was not in uniform for Sunday’s derby against Inter Milan and wasn’t named to the travel squad for Wednesday’s match at Palermo.