Kazakhstan's govt buys 21 pct stake in Halyk bank

* Govt buys 20.91 percent of common stock for $179 million

* Will inject $219 million through preferred share purchase

ALMATY, April 2 (Reuters) - The government of Kazakhstan has bought a 20.91 percent stake in the country's third largest bank Halyk (HSBKq.L) in line with its plan to boost the banking sector's capitalisation, the bank said on Thursday.

State welfare fund Samruk-Kazyna, which acts as the government's agent, has paid 27 billion tenge ($179 million) for the stake, Halyk bank said in a statement.

The government has earlier said it would invest up to $500 million in Halyk and buy up to 25 percent of its common stock. Halyk said on Thursday it expected to get another $219 million from the state through the sale of preferred shares.

Kazakh banks have been hit hard by the global financial crisis due to their reliance on foreign borrowing. The government nationalised Kazakhstan's largest bank BTA BTAS.KZ in February and plans to take over No.4 bank Alliance (ALLBq.L).

It also plans to buy up to 25 percent in No.2 bank Kazkommertsbank KKGB.KZ in a scheme similar to Halyk's. (Writing by Olzhas Auyezov; editing by Mike Nesbit)