* Curve hovers at four week lows OTC and on the EEX
* Spot prices climb again on tight supply, rising demand
FRANKFURT, July 25 (Reuters) - Europe's power curve traded at four-week lows early on Wednesday ahead of the publication of a European Commission plan to cut supply in the carbon emissions market to boost prices.
"Fuels are bearish which is dragging down power but carbon prices could jump briefly if the plan convincingly cuts CO2 permit supplies, " one trader said.
Apart from fuels prices, Europe's power industry has to factor in the cost of mandatory CO2 avoidance efforts into prices, where the price of emissions allowances sets the benchmark.
German Cal '13 baseload was unchanged at 47.75 euros ($58) a megawatt hour in the OTC market, the lowest since late June, having touched an intraday low of 47.50 euros.
The equivalent French OTC contract was last 5 cents down on the day at 49.65 euros.
On the EEX bourse, the German Cal '13 baseload contract was at 47.67 euros, the lowest since 47.50 euros on June 21.
EU carbon for Dec 12 delivery was 0.3 percent down at 7.18 euros a tonne. The EU Commission will publish details later on Wednesday on its plan to bolster the carbon Emissions Trading Scheme (ETS) by reducing a massive burden of surplus allowances.
Brent slipped to $102 a barrel as worries about oil demand from the troubled euro zone offset any gains to prices sparked by concerns about oil supply from the Middle East.
The euro zone's private sector shrank for a sixth month in July as manufacturing output nosedived, notably in Germany and France, the bloc's core markets.
Prompt power prices rose for a third day due to low wind power production and tight French nuclear power availability.
Power for Thursday gained 1 euro in Germany to 48.75 euros BD1DE-D and 90 cents in France to 49.75 euros, compared with day-ahead levels paid the previous day.
Midday peak-time solar capacity levels were expected to fall to near 10 GW by Saturday from nearly 20 GW currently utilised during midday peaks, while wind levels will remain at negligible levels up to the weekend, according to weather data.
Temperatures in Germany were at just under 30 degrees, having risen 3 degrees this week on average, while France saw level of over 30 degrees in the south and could spike at 35 degrees in some locations, boosting power demand for air conditioning.
German utility postponed an investment decision on a 3 billion euro offshore wind farm in the North Sea to early next year because the liability rules for such projects are still unclear, according to a media report. ($1 = 0.8275 euros) (Reporting by Vera Eckert; Editing by Alison Birrane)