* World stocks gain on Bernanke comments, M&A
* Wall Street likely to open up
* Dollar slips as BOJ move limited
By Jeremy Gaunt, European Investment Correspondent
LONDON, Aug 30 (Reuters) - World stocks put in modest gains and the dollar slipped on Monday, lifted by last week's assurance from the U.S. Federal Reserve that it will do what is needed to spur economic recovery.
Early indications were that Wall Street would also start on an up note.
Mergers and acquisitions continued to buoy European shares. Japanese stocks closed up nearly 1.8 percent, but only after paring earlier strong gains when the Bank of Japan made only minor tweaks in policy, disappointing markets looking for more aggressive action against deflation.
The yen rose after the decision as expectation of imminent market intervention to weaken the currency faded.
MSCI's all-country world stock index <.MIWD00000PUS> and the Thomson Reuters global stock index <.TRXFLDGLPU> both gained around 0.4 percent. MSCI's emerging market sub-index <.MSCIEF> was up 0.8 percent.
A major catalyst was Fed Chairman Ben Bernanke's playing down of the likelihood that the slowing U.S. economy might slip back into recession.
"(It) was reassuring, but predictably so. There was no big positive surprise," said Bernard McAlinden, investment strategist at NCB Stockbrokers in Dublin.
"As long as the economy stays out of recession, and we have some growth, the markets won't be too worried. The consensus is there won't be a double dip."
Trading in Europe was thinned by a holiday in Britain, but the FTSEurofirst 300 <
> was up 0.4 percent.News of mergers and acquisitions has been a factor in generally buoying stock markets in recent days.
On Monday, the buzz was around French aerospace parts maker Zodiac Aerospace <ZODC.PA> reportedly launching an offer for French conglomerate Safran <SAF.PA>. South Korean group POSCO <005490.KS> said it was considering a takeover of Elkem, a maker of silicon for solar panels, and a unit of Norway's Orkla.
French drugmaker Sanofi-Aventis <SASY.PA> also publicly disclosed its $18.5 billion cash offer for U.S. biotechnology company Genzyme Corp <GENZ.O>.
M&A activity in August had reached $228 billion by Friday, not far from the $260 billion record for the month hit in 2006, before the financial crisis.
BOJ SHUNS AGGRESSION
The yen rose against the dollar after the Bank of Japan failed to signal aggressive measures to curb yen strength at an emergency meeting, choosing only to expanded a fixed-rate fund supply scheme.
The central bank's moves were seen by investors as a symbolic gesture that will do little to halt the currency's climb which is hurting exports and may prolong deflation. [
]"People are once again putting on short dollar/yen positions, having reduced their long exposure ahead of the meeting," said Niels Christensen, currency strategist at Nordea in Copenhagen.
The dollar was down 0.5 percent against the yen <JPY=> at 84.78 yen, close to a session low of around 84.73 yen.
The dollar was also down 0.1 percent against a basket of currencies <.DXY>.
German government bonds resumed their climb following a steep fall late last week but held well below record highs struck recently with a public holiday in Britain dampening trading activity. (Additional reporting by Brian Gorman and Jessica Mortimer; Editing by Toby Chopra)