* MSCI world equity index up 0.25 percent to 305.94
* M&A, upbeat U.S. data lift sentiment
* Euro slips on Irish jitters; gold hits all-time highs
By Natsuko Waki
LONDON, Sept 27 (Reuters) - World stocks hit their highest level in nearly five months on Monday while oil prices rose as growing corporate merger activity and last week's upbeat U.S. economic data encouraged investors to buy risky assets.
Unilever has agreed to buy U.S.-based hair care firm Alberto Culver for $3.7 billion in cash. A source said China's Bright Food Group is exploring the purchase of Britain's United Biscuits in a possible $3.2 billion deal.
Corporate activity is increasing as companies take advantage of strong cash flows and historically low interest rates to look for bargains and expand their business.
U.S. stocks posted their fourth week of gains last week after data showing a rise in August business spending provided the latest evidence that the recovery is on firmer ground.
"We are now seeing a lot of corporate activity. I don't think we would see this unless there was a certain degree of confidence that the outlook was reasonably promising," said Mike Lenhoff, chief strategist at Brewin Dolphin.
"If you look at the overall background, we have got interest rates likely to remain where they are in the major economies for a long period of time, we have got a recovery that is under way and is likely to be sustained, and the underlying tone of some of the newsflow is strong." The MSCI world equity index rose a quarter percent to the level last seen early in May.
The Thomson Reuters global stock index rose around 0.3 percent.
The FTSEurofirst 300 index gained a quarter percent while emerging stocks rose 0.7 percent to their highest level since July 2008.
Thomson Reuters data showed that global mergers and acquisition activity announced so far this year totalled $1.678 trillion, surpassing volumes in the first nine months of 2009.
The activity in the June-September period totalled $599 billion, the third consecutive quarter of growth and up 25.6 percent from the same period in 2009, making it the strongest quarter for worldwide M&A since Q3 2008.
U.S. crude oil rose 0.1 percent to $76.58 a barrel.
EURO ZONE WORRIES
Encouraging corporate news aside, investors remained concerned about the outlook for the euro zone's banking sector.
The euro fell 0.3 percent to $1.3442, retreating from Friday's five-month high, after ratings agency Moody's cut Anglo Irish Bank's unguaranteed senior debt by three notches and its subordinated debt by six.
Investors have been nervous about possible restructuring of Anglo Irish Bank's subordinated debt as government guarantees for such instruments expire later this week.
The bund futures rose 45 ticks.
"Core debt is likely to stay more reactive to the periphery with nothing imminent to ease concerns," said Credit Agricole strategist Peter Chatwell.
"If the ECB does not start buying in a sizeable way, illiquid markets such as Ireland and Portugal could slide further, with the fear trade boosting Bunds in the short term."
The dollar held steady against a basket of major currencies. (Additional reporting by Atul Prakash; editing by Tim Pearce)