* FTSEurofirst 300 down 0.1 pct, Euro STOXX 50 down 0.2 pct
* Commodity sector drops with oil prices on nuclear deal
* Winning run inspired by Greek deal set to end
* Gjensidige, Kuehne und Nagel rise after earnings
By Alistair Smout
LONDON, July 14 (Reuters) - European stocks edged lower on Tuesday after a four-day rally, with weaker oil prices weighing on commodity stocks after Iran and six world powers agreed a landmark nuclear deal which could see sanctions on oil exports lifted.
The STOXX Europe 600 Oil & Gas EUR Price Index fell 0.8 percent, making it the top sectoral faller.
Oil prices fell more than a dollar. A Reuters survey of analysts had said that Iran would increase its oil exports by up to 60 percent within a year if a nuclear agreement was reached.
"A key question is now how quickly supply will now come online," Ashburton European equity fund manager, Veronika Pechlaner, said.
"The Iran deal was well advertised in advance, so it shouldn't come as a huge surprise. But it will take a few quarters to know the longer term effects."
The pan-European FTSEurofirst 300 index was down 0.1 percent at 1,570.33 by 0756 GMT, after gaining about 9 percent since last Tuesday on hopes of a Greek debt deal.
However, just hours after signing up to an austerity package in return for agreeing to talks on an 86 billion euro bailout, doubts were already emerging about whether Greek Prime Minister Alexis Tsipras would be able to hold his government together.
The euro zone's Euro STOXX 50 index was down 0.2 percent after hitting a two-week high on Monday.
Top faller on the FTSEurofirst 300 was RWE , down 2.3 percent after UBS cut its rating on the German utility firm to "sell" from "neutral".
Among risers, Norwegian non-life insurer Gjensidige rose 4.2 perecent after posting second-quarter pretax earnings that beat expectations.
Switzerland's Kuehne und Nagel International AG gained 3.8 percent after a 4.2 percent rise in earnings.
Europe bourses in 2015: link.reuters.com/pap87v
Asset performance in 2015: link.reuters.com/gap87v
Today's European research round-up (Editing by Louise Ireland)