Most Kenyans back new basic law, with changes--poll

* Most say law needs further amendment, but still back it

* Support for constitution greater than in June survey

NAIROBI, July 17 (Reuters) - Almost two-thirds of Kenyans intend to vote for a new constitution next month although just as many say it will need some amendments, an independent poll has found.

Angered by corruption, land ownership scandals and powerful politicians, Kenyans look set to approve the new legal framework to replace a constitution written at the time of independence from British colonial rule in 1963.

It would limit presidential powers, increase civil liberties and address longtime marginalisation of some tribes, forming a key plank in reforms seen as necessary to avoid a recurrence of the East African country's bloody post-election crisis in 2007-08.

A random countrywide survey of 3,002 respondents by pollster Strategic Research -- released on Friday -- showed 62 percent said they would vote "yes" for the new constitution, 20 percent would vote against it and 18 percent were undecided.

Analysts have a mixed forecast on the outcome, with many traders and analysts saying markets would take enormous confidence from the measure's peaceful passage into law.

But they also fear that regions populated largely by likely "no" voters could resort to violence if the "yes" side wins.

In a poll released in June by another researcher, Synovate, 57 percent of 2,000 people surveyed said they would vote "yes" -- down by seven percentage points since April -- and 20 percent said "no", while 19 percent were still undecided.

Guarantees of a new legal framework were central to a power-sharing deal in 2008, brokered by former U.N. chief Kofi Annan, that ended weeks of violence after a disputed election result that killed about 1,300 people.

The new poll showed 63 percent of respondents thought the draft constitution was a good document, but needed amendments while 25 percent said it was good and needed no changes.

Those opposed to the new constitution, including some ministers in the coalition government, are upset at what they feel is its failure to devolve sufficient power to the regions and at plans to cap private land holdings.

Christian church leaders are also urging a "no" vote due to a clause allowing abortions on medical grounds and recognition of Islamic courts dealing with divorce and inheritance.

Analysts say that many politicians, wanting to appear reformist, are rooting for the new law but, privately, would rather things remain as they are now.

Some of them have benefited from years of impunity and flagrant disregard for the rule of law and some Kenyans are concerned that a new charter will not produce swift change. (Reporting by George Obulutsa, Editing by Mark Heinrich)