* Kabel Deutschland files lawsuit at state court in Frankfurt
* Says Deutsche Telekom overcharged for use of cable ducts
* Says wants reduction of annual fees
* Says wants repayment of 273 mln euros of fees already paid
* Deutsche Telekom rejects charges, says its prices are "correct" (Adds details, background)
FRANKFURT, April 5 (Reuters) - Telecoms and cable firm Kabel Deutschland has filed a lawsuit against Deutsche Telekom, Germany's largest telecoms company, saying the former monopoly overcharged it for using its cable ducts.
Kabel Deutschland wants a two-thirds reduction of the roughly 100 million euros ($131 million) it pays Deutsche Telekom annually for the use of its cable ducts, pipes that house phone and internet lines, it said on Thursday.
Kabel Deutschland also wants Deutsche Telekom to repay about 273 million euros of fees already paid from 2004 to 2011, plus interest, it said. The lawsuit was filed at the state court in Frankfurt, a spokesman for Kabel Deutschland said.
Deutsche Telekom rejected the allegations, saying its prices were "absolutely correct", adding Kabel Deutschland's interpretation of the law was "wrong".
Telecommunications groups across Europe have been battling for years for cheaper use of the networks of former phone monopolies, which have in most countries remained the dominant players.
European telecoms lobbying group ECTA urged European Union regulators last year to cut fees charged by dominant operators for access to copper wire networks, arguing such firms enjoyed unfair subsidies.
Kabel Deutschland said it believes that it should pay the same level of fees to Deutsche Telekom as the national regulator, the Federal Network Agency, has set for VDSL lines - high speed internet access combined with phone lines.
"There are no differences between the regulated ducts and the ducts used by (Kabel Deutschland) which would justify a difference between the price payable by Kabel Deutschland and the regulated price," the company said.
Deutsche Telekom, though, said in response that the cable facilities used by cable network operators were indeed different from the regulated ones.
$1 = 0.7623 euros Reporting by Maria Sheahan; Additional reporting by Till Weber; Editing by Mark Potter