* Thuringia state premier says may aid Opel
* Opel works council says management not sticking to agreements
* Opel CEO says personnel costs need to be 25 pct - Bilanz
* Opel CEO says rules out factory closure - Bilanz (Adds quotes from Opel CEO, works council)
BERLIN, April 23 (Reuters) - The German state of Thuringia is ready to offer assistance to carmaker Opel in order to keep the region's Eisenach plant open, state premier Bodo Ramelow told Reuters on Monday.
The state could help with energy costs and property, he said, but added that it would only lend assistance if wage bargaining parties returned to the negotiating table.
It is unacceptable to use investment decisions to put the state of Thuringia "virtually under threat of blackmail", Ramelow said.
Of the three states in which Opel produces in Germany, he added: "The three states won't allow themselves to be divided."
France's PSA Group last year paid General Motors $2.6 billion for loss-making Opel and British sister brand Vauxhall and is now seeking to make savings.
Opel needs to cut personnel costs by up to 25 percent to make German sites competitive, Chief Executive Michael Lohscheller told German weekly Bilanz.
Any investment in the German sites is conditional upon them becoming competitive. Opel has no plans to shut down a German factory and will honour existing collective wage bargaining agreements, Lohscheller told the magazine.
In a separate interview with Automobilwoche, Lohscheller said it would not be able to start production of a new model in Germany in the first half of 2018 because there was no settlement with labour representatives about how to make German sites more competitive.
The German carmaker group's German works council on Monday insisted that Opel management was not honouring their side of the bargain.
"Lohscheller should tell the truth. The tariff agreements are not being adhered to in the product and project plans for factories and engineering," the companies works council said in a statement on Monday. (Reporting by Hans-Edzard Busemann Writing by Paul Carrel Editing by Maria Sheahan/Keith Weir)