The 20-year-old, who joined Watford on a season-long loan in the summer, has scored 16 goals in 29 appearances in the second tier of English football.
Watford had hoped to secure a permanent deal for the Czech, but Ondrej Chovanec has confirmed that there is vast interest in his client.
"At the moment, five Premier League clubs are interested in Matej. We want Matej to stay with Watford at least until the summer. We are not planning any rush move for him," Chovanec told reporters.
"He has been at the club for six months, everything has worked fine, he has been coached by a great manager and the people love him. We have no reason to change anything."
The identity of the clubs interested is not yet clear.