Stuttgart - Supporters of Chancellor Angela Merkel's conservatives remained divided Tuesday over whether to accelerate tax cuts to stimulate the flagging economy.

Her own Christian Democratic Union (CDU) toed the Merkel line that cuts funded by borrowing would not help. Merkel told the CDU annual conference the previous day that she would invest in highways and schools instead.

But the Christian Social Union, the CDU's counterpart in Bavaria state, re-iterated its call for instant reductions in income tax.

Peter Ramsauer, who heads CSU parliamentarians in Berlin, addressed the conference in Stuttgart and said such cuts were vital. Germany, which is officially in recession, is to hold a general election next September.

Friction between the "sister" parties on the income-tax issue has been going on for months.

Ramsauer said the government should take "a few from the bouquet of ideas" the CSU had been proposing since May. The CSU leader, Horst Seehofer, declined an invitation to address on Tuesday the conference, saying he was busy in the state capital Munich.

By a large majority, the CDU conference rejected resolutions calling for larger rebates on income tax.

Merkel is set to meet January 5 with CSU leaders and the leadership of her other coalition partner, the Social Democrats, to fix early 2009 economic policy.

Merkel has also flung down a gauntlet to other parties, saying she will tell voters that Germany should suspend its timetable to close down the nuclear reactors that generate a significant part of its electric power.

But the conference passed a resolution calling on the government not to build any new nuclear power plants.

In a signal that migration might also become an issue in next year's election campaign, delegates also passed a resolution calling for German to be declared Germany's official language in the constitution.

Party leaders warned the proposal would be divisive, since it would be seen as an attack on minorities who nurture their own languages and lifestyles. (dpa)