Marian Kello could just walk away from Hearts at the end of his current contract in the summer. The Slovakian goalkeeper was not involved in the weekend's game against St Johnstone in the Scottish Cup due to a "political issue", according to manager Paulo Sergio. Kello confirmed his omission, which is set to continue against Celtic at Tynecastle tomorrow night, is because he refused to move to Austria Vienna on transfer deadline day. Kello said: "I got into trouble with the club for not completing the transfer (to Austria Vienna). My current contract ends in the summer and I will decide what to do then. The interest from Celtic was certainly real, but ultimately they did not make a concrete offer, so I decided to stay a Hearts player for now. But I'm not going to negotiate a new contract - I'm leaving on June 30. I will wait for offers and I am open to different possibilities. I'll see how it ultimately develops." Kello added that Hearts' predicament is, at least in part, behind his decision.He said: "The club is for sale - the owner (Vladimir Romanov) has made that clear. Here you essentially have to look after yourself. The salary gets paid only after a delay. It is a difficult situation."