Cologne claim a bid from Ipswich Town for striker Milivoje Novakovic has been rejected.
Ipswich are in the market for a new forward, with Jim Magilton still trying to arrange a deal for Newcastle United's Shola Ameobi.
Magilton has been linked with a string of players over the summer, with Slovenia international Novakovic the latest target for the Championship club.
A reported offer of 3.5million euros (£2.8m) was lodged with Cologne, but the Bundesliga club insist Novakovic is not for sale.
The club's sporting director Michael Meier told Express newspaper: "Ipswich have made us a written offer that was not bad, but we will not sell Novakovic.
"He is not for sale."
Novakovic scored 20 goals in the German second division last season and has notched two goals in two appearances in the top flight so far this term.