* Dax set for longest streak of weekly gains since 1998
* Index up 0.1 pct; FTSEurofirst also up 0.1 pct
* Commerzbank in relief bounce after fine
* Sabadell falls as TSB bid raises risk of cap hike
By Francesco Canepa
LONDON, March 13 (Reuters) - Germany's Dax index was set for its longest streak of weekly gains since 1998 on Friday as traders added to their bets on an economic recovery in the euro zone, aided by a weak euro.
Euro zone indexes were flat to slightly higher, taking a breather after a week that saw them outperform their U.S. counterparts sharply as the single currency hit a 12-year low against the dollar.
The DAX, up 0.1 percent at 0856 GMT, was up 2.3 percent on the week and set for its ninth consecutive weekly gain, the longest winning streak in 17 years.
Commerzbank was the top riser on the index as it rose 3.4 percent, with traders citing relief that a U.S. fine announced on the previous day was in line with market expectations.
The export-oriented Dax has risen 20 percent since the start of the year as an aggressive bond-buying programme by the European Central Bank, which was announced in January and started this week, fuelled demand for stocks and pushed down the single currency.
"So much of the positives on the European market is in the price," Paul Chesterton, a senior trader at Peregrine & Black, said. "I can't help feeling it's looking a bit stretched here."
The pan-European FTSEurofirst 300 index was up 0.1 percent at 1,575.56 points.
Among the best performers on the index was French tyre-maker Michelin, which rose 2.6 as analysts at Citi raised their target price on the stock and reiterated their "buy" recommendation.
Spain's Sabadell fell for second day, however, after a banking source told Reuters the bank is considering a 1.5 billion euros ($1.6 billion) capital hike via a share issue to fund a possible bid for Britain's TSB, which was announced on Thursday. Its stock was down 2.1 percent.
Europe bourses in 2015: link.reuters.com/pap87v
Asset performance in 2015: link.reuters.com/gap87v
Today's European research round-up
Editing by Toby Chopra