GLOBAL MARKETS-Stocks heading for best weeks in six ahead of Yellen, Draghi speeches

* Graphic: World FX rates in 2017 http://tmsnrt.rs/2egbfVh

* World shares head for best week in six, EM leads the way

* Dollar up on yen ahead of Jackson Hole meetings

* Wall Street looking to shake off political concerns

* Oil prices rise as Hurricane Harvey nears

* Pound down for fourth straight week against most currencies

* Euro rises after upbeat German data

By Marc Jones

LONDON, Aug 25 (Reuters) - World stocks climbed toward their best week in six on Friday, as a near three-year high in emerging market shares and a roaring rally in metals bolstered the year's global bull run.

Moves were mainly small ahead of speeches later by Federal Reserve and European Central Bank heads Janet Yellen and Mario Draghi at one of the highlights of central banking calendar, the Jackson Hole, Wyoming, symposium, but there was some traction.

European shares overcame an early wobble after reassuring business confidence data from Germany and as the week's 3 and 7 percent rises in metals copper and nickel gave the region's miners a 4 percent weekly gain.

London's FTSE, which has a heavyweight mining contingent, led the way with a 0.4 percent rise on the day and 1.5 percent for the week. It was also being boosted by the fourth straight weekly drop in the Brexit-bruised pound, which helps internationally-earned profits.

Fast (Shanghai: 600391.SS - news) charging emerging markets helped Asia secure a 1.6 percent weekly rise, while Wall Street looked set to open higher despite a rumbling row for Donald Trump as the United States approaches its self-imposed government debt limit.

"Our current assessment of the overall risk and reward picture keeps us overweight global equities in our tactical asset allocation," UBS Wealth Management chief investment officer, Mark Haefele, said in a monthly note.

"Earnings and economic growth are strong enough, and central bank policy is still sufficiently loose to suggest that, in the absence of a shock, markets are likely to trend higher over the next six months."

With (Other OTC: WWTH - news) focus increasingly turning to Yellen and Draghi's speeches, scheduled for 1400 and 1900 GMT respectively, currency and bond market traders began to square up their positions.

The dollar added marginally to its best week against the Japanese yen in seven as it hovered at 109.66 yen.

But it couldn't keep the high-flying euro at bay after the German data. The euro zone currency has had another strong week. It is back about $1.18 and is at its highest against the pound in eight years barring sterling's "flash" crash last October.

FARCE CEILING

Emerging markets have been a strong driver of the global stocks rise this year.

MSCI (Frankfurt: 3HM.F - news) 's 24-country EM index hit a near three year high on Friday. Asia-Pacific shares ended the week 1.6 percent higher, having shrugged off the overnight dip on Wall Street as a rift between Trump and Congress over the country's debt level rumbled on.

In a post on Twitter (Frankfurt: A1W6XZ - news) , Trump said Congress could have avoided a legislative "mess" if it had heeded his advice on raising the amount of money the government can borrow.

Since 1960, Congress has acted 78 separate times to permanently raise, temporarily extend, or revise the definition of the debt limit, 49 times under Republican presidents and 29 times under Democrat ones.

But the Trump factor is making markets jittery. His latest tweet came after he said on Tuesday that he would be willing to risk a government shutdown to secure funding for a wall along the U.S.-Mexico border.

The standoff has also been one of the reasons why U.S. bond yields have nudged up for a second week running. Fed head Yellen is not expected to give any bold signals on raising U.S. interest rates later but she could bolster the view that they will at least continue to go higher.

There is just as much focus on Draghi, though he too is expected to avoid inflaming the debate on when the ECB scales down its 60 billion-euro-a-month stimulus programme.

Portugal's 10-year bond yield rose to its highest level in almost a month on Friday and was set for its biggest weekly jump since January, as renewed focus on the ECB's plans weakened sentiment towards lower-rated euro zone debt markets.

METALS SHINE

In commodities, oil prices rose on expectations that one of the strongest U.S. hurricanes in more than a decade could hit U.S. and Gulf of Mexico production.

Hurrican Harvey as it has been named, is packing winds of up to 125 miles per hour (200 kph), and is forecast to drive a 12-feet (3.7-metre) surge in sea levels and dump up to 35 inches (97 cm) of rain over parts of Texas.

U.S. crude futures rose 0.7 percent to $47.75 a barrel, and global benchmark Brent advanced 0.7 percent to $52.43. They had fallen as much as 2 percent on Thursday as refiners in the path of Harvey shuttered production.

Industrial metals were heading for a dazzling week. Copper remained near a three-year high hit on Thursday on signs of stronger demand in top consumer China while inventories in London warehouses fell.

Nickel which is used in stainless steel was up more than 6 percent for the week and benchmark Chinese iron ore futures were up for an eighth straight week.

Gold meanwhile was up slightly at $1,287.07 an ounce, heading for a 0.2 percent gain for the week.

"I share the view that copper is over-extended and that a correction is due, but every correction needs a trigger," said Julius Baer (LSE: 0QO6.L - news) , commodities research analyst Carsten Menke in Zurich.

"One potential trigger is a rebound of the U.S. dollar, which could come over the weekend, depending on what is discussed in Jackson Hole, or from U.S. economic data."

For Reuters Live Markets blog on European and UK stock markets see reuters://realtime/verb=Open/url=http://emea1.apps.cp.extranet.thomsonreuters.biz/cms/?pageId=livemarkets

(Reporting by Marc Jones Editing by Jeremy Gaunt.)