Craig Levein has admitted Willo Flood may prove too expensive to retain at the club come the summer.

The Irishman wants to stay at Tannadice when his loan from Cardiff City expires at the end of the season and United are keen to bring him on board long-term, but manager Levein will not be able to pay a significant transfer fee should the Welsh club demand one.

Flood, man-of-the-match in the recent CIS Insurance Cup final, signed on at Ninian Park for £200,000 from Manchester City in 2006, and impoverished Cardiff are likely to look to recoup most of that outlay, hence pricing Levein out.

"I'd like to keep Willo because he has done well for us but that may prove too expensive to achieve," said Levein.

"I am realistic enough to recognise that the financial aspects involved would probably be beyond us."

Meanwhile, Levein has heaped praise on goalkeeper Lukasz Zaluska for keeping four clean sheets in his last five matches.

The Pole faced the unenviable task of replacing Gregorz Szamotulski in January, but has stepped in to fill his countryman's boots and the manager believes that the highly rated 25-year-old will continue to improve.

"Lukasz had a shaky start for us, but perhaps that wasn't entirely unexpected," said Levein. "Not only was he having to follow in the footsteps of Grzegorz Szamotulski, which anyone would have found difficult, he was also having to overcome the fact that despite being in his mid-20s he hasn't had a lot of first-team football in his career.

"But, as I thought he would when I signed him, he's improved as he's gone along and, overall, I think he's done well for us.

"He's made a couple of errors but also pulled off a few important saves, most notably on Saturday against Motherwell, against Gretna at a crucial time in the game and in the cup final.

"With guys like Lee Wilkie, Darren Dods, Garry Kenneth, Christian Kalvenes, Danny Grainger, Sean Dillon and Mihael Kovacevic playing in front of him, and the kind of midfield we have, I wouldn't have expected him to lose too many goals.

"But I've still been delighted with him."

The United manager also poured scorn on suggestions that he could return to Hearts in the summer.

Vladimir Romanov, the Hearts owner, is searching for a new manager and has Levein high on his wish list, but the former Tynecastle favourite has no desire to move back to Edinburgh.

"I suppose me getting linked with them is not a huge surprise," he added. "All I can do, when it happens, is stress how happy I am here at United and that I have no intention of going anywhere."