* FTSEurofirst 300 falls 3 pct to 15 months lows
* BHP Billiton takes $7.2 bln charge on U.S. assets
* Oil and gas sector under pressure as crude drops below $30
* Syngenta up on M&A hopes, H&M boosted by strong December sales,
By Danilo Masoni and Alistair Smout
MILAN/LONDON, Jan 15 (Reuters) - European shares fell on Friday to their lowest since December 2014, hit by losses in commodity-related stocks as BHP Billiton announced a major writedown and oil fell below $30 a barrel.
Some investors said stocks were deeply oversold and flagged hopes of more central bank intervention to help reverse the trend after three straight week of losses.
BHP Billiton shed 6.8 percent, the top faller on the pan-European FTSEurofirst 300, after saying it would write down the value of its U.S. shale assets by $7.2 billion. That cemented expectations the company will be forced to cut its dividend for the first time in more than 25 years.
The STOXX Europe 600 Basic Resources index was down 6 percent, with Rio Tinto, Glencore and Antofagasta also among top fallers.
All four stocks also suffered from target price cuts by Japanese bank Nomura. Copper has hit a new 6-1/2 year low this week and was set for its second straight weekly loss.
The oil and gas sector was also under pressure, down 3.7 percent. Brent and U.S. crude both fell below $30 a barrel, as markets braced for more oil supply from Iran.
"Stocks are being driven by oil, and given that the Iranian sanctions are due to be lifted, that's causing even more nervousness about this glut of oil that we have," said Zeg Choudhry, managing director of LONTRAD.
Concerns over commodities and Chinese growth have marked a rocky start to the year for global markets. Chinese shares closed at their lowest level since December 2014, rocked again by falling oil.
The FTSEurofirst 300 was down 3 percent at 1,294.69 points by 1514 GMT, set for its third straight weekly loss. It fell 6.7 percent last week when China allowed its currency to devalue and is down another 1.7 percent.
Enrico Vaccari, fund manager at Italy's Consultinvest, said investors were testing central banks to see whether they had ammunition left to prop up markets and the economy.
"There is a symbolic poker match between the market and central banks. I don't think China and oil are the real problem here," he said "The market is trying to force the hand of central banks in the hope they unleash more stimulus. So far there has been no answer but at some point it will arrive."
The European Central Bank holds its next policy meeting on Thursday.
Among other fallers, Brenntag dropped 5.1 percent after the chemicals firm was cut to "hold" from "buy" by Deutsche Bank.
The top riser was Syngenta, up 2.6 percent, following a Bloomberg report saying its board had voted in favour of pursuing advanced takeover talks with ChemChina.
H&M was up 1 percent after it posted a rise in sales in December which beat forecasts.
Today's European research round-up (Additional reporting by Danilo Masoni in Milan; Editing by Toby Chopra)