HONG KONG/LONDON - Standard Chartered (StanChart) on Tuesday announced its largest-ever share buyback worth $1.5 billion and lifted its earnings outlook for this year betting on strong economic growth in its core Asian markets and plans to rein in costs.

The bank's Hong Kong-listed shares rose 4% after the results.

StanChart's statutory pre-tax profit for the first half rose 5% to $3.49 billion. That compared with $3.32 billion a year earlier and the $3.46 billion average of 15 analyst estimates compiled by the bank.

The London-headquartered lender, which earns most of its revenue in Asia, now expects operating income to grow more than 7% on a constant currency basis compared with its previous projection of between 5% and 7%.

Asia-focused global banks including StanChart and rival HSBC have benefitted in recent years from higher interest rates and relatively higher economic growth and wealth generation in the region.

"We are uniquely positioned to take advantage of significant growth opportunities that will continue to come from the markets in our footprint, generating value for our clients," StanChart CEO Bill Winters said in a statement.

"Global trade and investment will continue to grow and is expected to be anchored in Asia, Africa and the Middle East, and in Asia wealth creation is also expected to outpace that in the rest of world."

But in China, slowing economic growth and the country's property sector crisis have been a concern for Western banks. StanChart has made provisions totalling $1.2 billion for potential bad loans in China's commercial real estate sector so far this year.

The property market recovery in China "remained slower than expected amidst government support measures", and the bank continues to monitor its portfolios, Stanchart's Chief Risk Officer Sadia Ricke said.

StanChart said the $1.5 billion buyback was expected to shave 60 basis points off its core capital buffer ratio, which rose to 14.6% at the end of June from 13.6% in the first quarter and was above the bank's 13%-14% target range.

(Reporting by Selena Li in Hong Kong and Lawrence White in London; Editing by Sumeet Chatterjee and Edwina Gibbs)