* CGT union defends power cuts against pension reform

* Central bank, clinics, fire brigades hit - minister

* Presidential office says Macron won't back down

* Unions in talks with French prime minister (Adds historian, union, Macron comments, opinion poll)

By Michel Rose and Bate Felix

PARIS, Dec 18 (Reuters) - France's trade unions on Wednesday defended their decision to cut power to thousands of homes, companies and even the Bank of France to force the government to drop a wide-ranging pension reform.

The power cuts, illegal under French law, deepened a sense of chaos in the second week of nationwide strikes that have crippled transport, shut schools and brought more than half a million people onto the street against President Emmanuel Macron's reform.

Asked on French radio whether the power cuts weren't a step too far, Philippe Martinez, the head of the hardline CGT union, said the cuts were necessary to force Macron to back down.

"I understand these workers' anger," the mustachioed union leader said. "These are targeted cuts. You'll understand that spitting on the public service can make some of us angry."

Following a meeting with government officials, he hinted at further cuts, saying "we may amplify these kinds of methods".

Macron condemned the power outages "in the strongest of terms" during a cabinet meeting, a government spokeswoman said. But his office said the president was open to "improvements" to his reform plans ahead of a new day of talks between his prime minister and union leaders.

After the talks, the leader of the more moderate CFDT union said the government had shown more "openness" but that a deal was still "very far" from being agreed.

The government is keen to reach a truce before Christmas, when millions of French people travel to spend the holiday with their families. French hotels, cafes and stores are already feeling the pain of the strike.

Macron's transport minister condemned the power cuts, which affected at least 150,000 homes on Tuesday according to the power grid, and said the government would ask the grid company to file complaints.

"FAR FROM NORMAL"

"Cutting power to blue-chip companies, prefectures, shopping malls, that's already rather questionable," Elisabeth Borne said. "But clinics, metro stations, fire brigades and thousands of French people also saw power cuts. This is far from normal ways of striking."

Power cuts are an old union tactic that started at the turn of the previous century and were used after World War Two but dropped later on because of fears of a public backlash, said Stephane Sirot, a historian at Cergy-Pontoise university.

"In the 90s, it was mostly set aside because some union members were worried it could turn public opinion against them," Sirot told Reuters. "So they adopted other methods, like cuts targeting the homes of the elite."

This time, unions may feel opposition to the reform is wide enough to warrant more radical action. Some 57 percent of French people oppose the reform, a 11-point increase over one week, according to an Elabe poll for BFM TV.

However, 63 percent of the French want a truce during the end-of-year holiday period, the poll showed.

Macron wants to turn the myriad of French pension systems into a single points-based one. That would force staff at state-owned firms such as railway SNCF or utility EDF, who enjoy more generous pension plans than private-sector workers, to work longer.

SNCF train drivers currently can retire at just over 50, for instance, against 62 for those in the private sector. That means taxpayers have to plug the SNCF pensions deficit to the tune of 3 billion euros every year.

Martinez said that rather than reducing the pension system's deficit by increasing the retirement age, the government should increase corporate social security contributions, tax financial products and make internet firms pay social security charges.

The government argues that increasing pensions contributions would make labour more costly and force young people to pay yet more to fund French pensions. (Additional reporting by Marine Pennetier, Sudip Kar-Gupta and Caroline Pailliez Editing by Mark Heinrich)

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