Arsenal, Chelsea, and Manchester United have been told to increase their bids for Borussia Dortmund striker Robert Lewandowski.
Lewandowski has been linked with Arsenal and Manchester United for some time, while reports on Saturday suggested that Chelsea had tabled a bid in the region of £13million for the 23-year-old.
Lewandowski is known to be keen on moving to the Premier League, and his representative has confirmed that offers have been received from some top English sides.
But Maik Barthel insists clubs will need to up their offers for the Poland international if a deal is to go through.
"Unofficially there are offers from English top clubs." Barthel told Goal.com.
"We respect the contract situation in Dortmund and don't want to take part in speculation.
"A £13million transfer fee is not suitable."
Lewandowski, who has also been linked with Tottenham, this past week told Bild he was looking to secure a move to the Premiership and has previously been quoted as saying he would find it hard to achieve anything else with Dortmund.
The forward has two years left on his contract with the Bundesliga outfit.