Luton Town have made a new offer for LDU Quito midfielder Oscar Zambrano.
A Luton delegation have been in South America this week for talks with Quito for the youngster.
Quito chief Esteban Paz said on Radio Mach Deportes: "There is interest from Luton Town for scar Zambrano.
"In Argentina we had a short meeting, the offer is $4.5 million, but it does not meet our expectations.
"In the negotiation we must be careful with Oscar's rights and resources, and we have told him so."
Manchester United and Ajax are also keeping tabs on developments.