* Czech reshuffle looms as row threatens coalition
* Defence minister and PM ally offers to resign
* Government wants to reform pensions, public health
(Adds PM comments, defence minister, details)
By Robert Mueller and Jason Hovet
PRAGUE, April 11 (Reuters) - Czech Prime Minister Petr Necas took steps on Monday to sack two ministers from a coalition partner as graft scandals threatened to topple the government.
The scandals have shaken the centre-right cabinet as it struggles to agree on reforms of the pension and public health systems to cut the budget deficit.
President Vaclav Klaus, citing recent periods when the country of 10.5 million people was without a functioning administration, said he could not agree to remove the ministers until he had a clearer idea of how the government would operate.
"Before I accept a resignation or resignations, or before I make a decision about the dismissal of one or another minister, I will require a plan... for the further functioning of the Czech government from the prime minister," said Klaus, who has the final say on dismissals from the cabinet.
"My interest is to not allow us to go into any disorganised, chaotic process," he told a news conference.
INVESTIGATION OPENED
Transport Minister Vit Barta resigned on Friday after reports surfaced in the Czech media that he had paid deputies from his Public Affairs party to secure their allegiance.
Barta denies any wrongdoing.
Police opened an investigation into graft charges made by two Public Affairs deputies on Monday, an anti-corruption police spokesman said.
Necas submitted Barta's resignation to Klaus and also proposed sacking Interior Minister Radek John, who chairs Public Affairs, and Education Minister Josef Dobes.
The coalition's austerity measures have been praised by investors but, with the scandals, have seen its support halve from the 60 percent it enjoyed after an election last year.
A break-up of the coalition would not necessarily cause the collapse of the government, which holds the largest parliamentary majority since the Czechs split with Slovakia in 1993.
Public Affairs has threatened to withdraw support from the government unless the removal of its ministers is accompanied by the departure of ministers from the other two parties, including Finance Minister Miroslav Kalousek, who is vice-chairman of the other junior partner, TOP09.
Without Public Affairs, the government would need seven more votes to have a majority in the 200-seat lower house. It could do this, for instance, by securing the votes of party rebels from Public Affairs who do not always back the party line.
In another blow to Necas, Defence Minister Alexandr Vondra, offered to resign after coalition partners called for his departure over allegations he oversaw an overpriced services contract during the Czech EU presidency in 2009.
Vondra, who is an ally of Necas in their Civic Democrats party, has denied any wrongdoing.
Necas declined to comment on Vondra.
But he told reporters after meeting Klaus that the three-party coalition would continue, even if there were further personnel changes.
"Of course the debate will continue, because one thing is the departure of someone from the government, but another thing is the arrival of someone new, and perhaps other changes in the government that may occur," he said. (Writing by Jason Hovet; Editing by Jonathan Lynn)