It is called supply and demand.
Long time ago when I was in Banking : I recommended that there should not be Saving account and pay interest. Saving account should be similar to Checking account like US.
ICIS bank are utilizing their Saving to Various loan activities with higher Interest rate than CD/Fixed Deposit.
To some point people may put money in reputed bank even the interest rate is lower because of security.
Those who are offering Higher Interest rate may be investing in extremely risky investment like Barnie Madoff.
You have read may finance business were involved on such activities and filed bankruptcy.