A man has been arrested in connection with the theft of 900 FA Cup semi-final tickets.
A Royal Mail van carrying the Manchester City tickets was targeted in the city on Friday.
Yesterday police arrested a 39-year-old man on suspicion of theft.
The arrest came after officers investigating the theft carried out three search warrants in the city.
The man, who was not arrested at any of the addresses searched by police, has been bailed pending further inquiries
A spokesman for Greater Manchester Police said no tickets were recovered as a result of the warrants and added that inquiries were continuing.
The thieves struck shortly before 7.50pm on Friday in Ashton New Road, Manchester, when two bags of special delivery mail were stolen from a Royal Mail van.
It is feared the tickets for the upcoming derby clash against Manchester United on April 16 will be sold on the black market.
A statement released by the club said: "Manchester City are working closely with Greater Manchester Police and Royal Mail in connection with the theft of Special Delivery mail items from a Royal Mail van on Friday.
"A number of tickets for the FA Cup semi-final at Wembley Stadium were stolen. All supporters impacted by the theft will be contacted by the club in the coming days."
The statement concludes: "Supporters are strongly advised not to purchase tickets from unofficial sources.
"Only tickets purchased direct from the club will be valid for the game."
The tickets are being re-issued to Manchester City by Wembley Stadium.
A stadium spokesperson said: "Wembley Stadium can confirm that a number of tickets that were stolen for the upcoming FA Cup semi final between Manchester City and Manchester United will be re-issued to Manchester City.
"The original tickets that were stolen have been cancelled on the stadium's access control system.
"Only the tickets for these specific seats that are now being re-issued to Manchester City will be valid on the day.
"The stadium will continue to work very closely with the Metropolitan Police Service in planning for this event."