(Reuters) - Most Southeast Asian stock markets rose on Wednesday on optimism that European leaders will take strong steps to resolve the region's debt crisis at a summit later this week.    

Buyers looked for counters which were expected to show resilience in the face of global economic weakness, especially those which have been left with undemanding valuations after recent losses, brokers said.    

The benchmark Nikkei added 1.7 percent to 8,722.17, its highest close in four weeks and ending above its 75-day
moving average for the first time since late October. Last time it topped the average it managed to maintain that position for less than two days.    

The broader Topix index gained 1.6 percent to 749.63.     

Leading gainers, Thailand's benchmark SET index rose 1.6 percent to the highest in three months, while Singapore's Straits Times Index finished up 1.2 percent, also hovering around their highest since mid-November.    

The Thai market extended its recent gains to a seventh consecutive session and is expected to advance further by year-end, strategists said.    

Sukit Udomsirikul strategist at broker SCB Securities expected fund buying to lend support.    

Foreign investors and domestic institutions would be buying. The EU summit this week is an overall positive development of the debt crisis in the continent. We have seen some short covering activity so far, he said.    

Jakarta's Composite Index rebounded 1.1 percent after Tuesday's 0.7 percent loss, while the Philippine's main
index rose 0.8 percent, reversing a 0.2 percent loss the day before.    

According to Thomson Reuters data, the Philippines added $11.5 million in inflows, bringing inflows so far this month to $110 million.    

The Philippine stock market gained 2.7 percent so far this year, making it Asia's best performer.    

Stocks in Malaysia edged up 0.1 percent while Vietnam fell for a second day, easing 0.8 percent.    

Asian shares and the euro gained on Wednesday on hopes that the threat of mass credit rating downgrades will pressure European leaders to come up with a convincing framework for resolving the euro zone debt crisis at a crucial summit later this week.    

MSCI's broadest index of Asia Pacific shares outside Japan  rose 1.3 percent by 0927 GMT.    

But gains have been capped by wariness that any agreement among fractious European leaders may again prove too nebulous and too conservative to halt the global fallout from the region's debt crisis.

Among individual stocks, Singapore property developer CapitaLand Ltd rose 2.4 percent, buoyed by hopes it could benefit from spinning off of its assets into trusts and as its valuations looked cheaper than its peers.     

Thai refiner IRPC Pcl surged 7.6 percent, its biggest daily gain since January, on expectations that stronger margins for some of its petrochemical products will boost profitability next year.
    
Among gainers, Indonesia's top firm PT Astra InternationalTbk rose 1.8 percent and Malaysia's Pavilion Real Estate Investment Trust Bhd made a positive trading debut, ending at 1.02 ringgit against an initial public offering price of 90 sen each.    

(Additional reporting by Singapore bureau and by Hideyuki Sano.)