* Four countries sell combined 15 bln euros of debt
* Safety bid helps German auction after failures
* Italy pays highest yield since July 2015 on 3-year bond
* Geopolitical tensions continue to roil markets
* Euro zone periphery govt bond yields tmsnrt.rs/2ii2Bqr (Adds Dutch, Finnish bond prices)
By John Geddie
LONDON, April 12 (Reuters) - Around 15 billion euros of debt sales coming on top of geopolitical worries weighed on euro zone bond markets on Wednesday, pushing yields higher on the region's low-rated bonds.
Simmering political and diplomatic tensions kept demand firm for safe-haven assets, allowing Germany to shrug off recent failed auctions to sell 2.435 billion euros of 10-year bonds despite yields near multi-week lows.
Dutch and Finnish yields also fell to multi-week lows; the yield on 10-year Dutch government bonds dropping below 0.30 percent for only the second time since Nov. 9.
But investors remain wary of riskier assets. Italy had to pay up to sell 10 billion euros of long-term debt - the yield offered on its three-year bond was the highest since July 2015 .
Portugal sold 1.25 billion euros of five- and eight-year bonds and Ireland issued 1.25 billion euros of six- and nine-year bonds.
"There is a bit of weight from issuance, but what is really driving the direction of markets at the moment is geopolitics," Rabobank strategist Matt Cairns said, adding that trading was thin as Easter holidays approached.
The Syrian conflict has been the centre of concern, since it puts the United States on a collision course with Moscow, allies of Syrian President Bashar al-Assad. Fraying nerves further, North Korea warned on Tuesday of a nuclear attack on the United States at any sign of American aggression .
For European investors, France has been the focus. Far-left veteran Jean-Luc Melenchon is surging in the polls, joining another anti-EU candidate, Marine Le Pen, among the contenders for the presidency. The first round of voting is on April 23 .
German 10-year yields - the bloc's benchmark - were unchanged on the day, holding just above a five-week low of 0.192 percent hit on Tuesday.
Yields on lower-rated bonds from the likes of Italy, Spain and Portugal were up 2 to 4 bps on the day.
Diplomatic tension is the latest factor tarnishing an otherwise brightening outlook for global growth.
Economic institutes in the bloc's biggest economy Germany said on Wednesday that uncertainties linked to possible protectionist policies by the United States and a lack of clarity over Britain's divorce talks with the European Union cloud the outlook for growth.
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Editing by Larry King