* Relatives of ex-minister were removed from possible tax dodgers list -officials
* Former finance minister denies tampering with list
* PASOK party expels him over "Lagarde List" affair
* Papaconstantinou to face parliamentary probe, government says
By Harry Papachristou
ATHENS, Dec 28 (Reuters) - Greece's government backed calls for a parliamentary probe into former finance minister George Papaconstantinou on Friday after prosecutors found that names of his relatives had been deleted from a list of possible tax cheats he handled when in office.
Papaconstantinou, 51, who negotiated Greece's first international bailout in 2010, denied he changed the list after receiving it from French authorities two years ago, saying he was not aware any family members were on it.
The revelation adds a new twist to a case that has infuriated austerity-struck Greeks, angry at the government's failure to crack down on the tax evasion that has contributed to the country's financial crisis.
The original list included the names of three people with family ties to Papaconstantinou who were later removed, as Greek officials confirmed when they received a fresh copy of the list, one court official said on condition of anonymity.
"It was altered by Greek hands," the official said but did not say who might have been responsible for the change.
A second court official confirmed the information. Both said the fact that the names were on the list did not mean the account holders had done anything illegal.
Papaconstantinou issued a statement strongly denying he tampered with the list.
"I have in no way tampered with the evidence," said the former socialist minister. "If there are any accounts on the list concerning members of my wider family, I did not know this until today... I will not be turned into a scapegoat in this case."
But Papaconstantinou's own Socialist PASOK party expelled him from its ranks, saying he had mishandled the case.
"An obvious and enormous issue of responsibility arises for Mr. Papaconstantinou, who handled the issue in the worst possible way," said PASOK in a statement on Friday. "It is clear that Mr. Papaconstantinou is no longer part of PASOK".
The co-ruling Democratic Left party, the junior partner in Greece's three-party coalition, requested a parliamentary probe into Papaconstantinou.
"The penal procedure before parliament must be set in motion for the former minister... to fully investigate the case," said the party's leader Fotis Kouvelis.
The government agreed with Kouvelis's request, its spokesman Simos Kedikoglou said in a statement later on Friday.
Papaconstantinou, whose wife is Dutch, is currently in the Netherlands where he usually spends Christmas, a person close to him told Reuters.
Papaconstantinou served as finance minister from October 2009 to June 2011. He testified in parliament in October that he had passed about 20 names in the list to the financial crimes squad for checks. Drawing jeers from MPs, he said he then handed a CD with the data to an aide who appeared to have misplaced it.
The list contains hundreds of names of Greek account holders at global bank HSBC in Switzerland, which authorities want to investigate over suspected tax evasion.
France originally handed over the list to Athens in 2010. But former Greek government officials did little to act on it, fuelling public anger and prompting suspicion that some names were erased before it was given to parliament earlier this year.
To put an end to the confusion, Greek prosecutors travelled to Paris last week to examine the original list. They spent six days cross-checking the two documents to find out if any names were removed.
The list originates from wide-ranging data stolen by a former HSBC employee, which Paris obtained. Greeks have dubbed it the "Lagarde List" after Christine Lagarde, the head of the International Monetary Fund who was French finance minister when the list was originally handed over in 2010.
"The Lagarde List affair reflects in the most eloquent way the corruption, lawlessness and disease of the (political) system," the main opposition radical leftist Syriza party said in a statement.
Unlike other authorities around Europe who used the data to pursue cases of suspected tax evasion, Greek authorities kept it in their drawers.
Greece has so far failed to convict any prominent figures for tax evasion, fuelling popular disenchantment with a political class that promised to force the wealthy to share some of the pain of the debt crisis.
Austerity measures taken as part of the country's EU/IMF bailout have wiped out a fifth of economic output, hammering living standards.