* Italians don't buy tax refund pledge
* Berlusconi closes gap with centre-left but not enough
* Monti disappoints
By Barry Moody
ROME, Feb 5 (Reuters) - Most Italians do not believe Silvio Berlusconi's promises to cut taxes, despite a "shock proposal" to pay back a hated housing levy in a last lap attempt to win this month's election, two new opinion polls showed.
One of the surveys, published by SWG pollsters on Tuesday, also indicated the centre-left election frontrunners were making a slight recovery after previously losing support because of a banking scandal.
Another poll, by Demopolis on Monday night, said 51 percent of Italians did not believe Berlusconi's weekend pledge to immediately abolish the IMU property tax and pay it back, a proposal that was mocked by his opponents as an empty and impossible vote-buying trick.
Undermined by a lurid sex scandal, Berlusconi, 76, was hounded out of power and replaced by technocrat Mario Monti in November 2011, as Italy slid towards a Greek-style debt crisis.
The billionaire media tycoon spent most of next year in the shadows but has launched an astonishing comeback since December to halve the gap with the centre-left to around 5 points, although most pollsters think he still cannot win the election.
The resurgence of the master communicator, based on a blitz of television appearances and constant attacks on Monti's tax hikes, has raised the spectre of instability after the vote which is starting to worry investors.
SWG's poll, taken on Monday, showed Berlusconi was the least credible on taxes among all the political leaders fighting the Feb. 24-25 election, convincing only 18 percent of those surveyed.
Centre-left leader Pier Luigi Bersani was the most credible on 27 percent, just ahead of anti-establishment 5-Star Movement leader Beppe Grillo, a Genoese comedian.
Outgoing premier Mario Monti, the favourite of foreign investors, was fourth most credible, one above Berlusconi.
CENTRE-LEFT STILL AHEAD
SWG vice president Maurizio Pessato told Reuters he believed Berlusconi's surge had now stabilised and that most voters did not believe his sweeping tax cutting proposals.
SWG had the centre-left on 33.6 percent, up 0.8 percent over a week ago, and 5.5 percent ahead of Berlusconi's centre-right coalition, although the latter also gained slightly.
The Democratic Party (PD), biggest group on the centre-left, has suffered from a scandal over murky derivative trades and corruption allegations at Monte dei Paschi bank, with which the party has historic local connections in Tuscany.
Last week SWG showed it losing 1.6 percent support over the scandal but it now seems to be pulling back support.
Pessato said the most likely result of the election was that Bersani would fail to win control of the Senate and would need to join an alliance with Monti to govern. The centre-left is seen as winning a comfortable victory in the lower house.
Berlusconi's rise has ironically increased the chances of such a Senate result, which would reassure markets, by threatening Bersani's margin of victory.
The SWG survey showed Monti failing to realise the hopes of investors and foreign governments that he could bring a radical shake-up of Italy's discredited political system and push forward his programme of fiscal rectitude.
He is stuck on 13.3 percent, well short of his 20 percent target and nearly one percent down on a week ago.
He was eclipsed by Grillo's movement which was stable on 18 percent. The fiery comedian has built unprecedented support because of anger over a deep recession, rising unemployment and a string of political scandals. He calls Monti "Rigor Montis" and all traditional politicians "zombies".
Berlusconi seems to be taking extra votes by reinvigorating some disillusioned centre-right voters, but the electorate remains volatile.
Pietro Vento, head of Demopolis pollsters, estimated only about 60 percent of voters had made a final decision, leaving everything to play for in the final three weeks of the campaign.
According to SWG, Berlusconi's strongest supporters are self employed workers or entrepreneurs, followed by housewives - despite allegations of sex parties with aspiring starlets which have emerged during his Milan trial for having sex with an under age prostitute. (Writing by Barry Moody; Editing by Jon Boyle)