ZURICH (Reuters) -UBS announced changes to its executive board on Wednesday as the Swiss bank presses ahead with its integration of fallen rival Credit Suisse.

Switzerland's biggest lender appointed Aleksandar Ivanovic to lead its $1.6 trillion asset management business, replacing Suni Harford who is retiring.

Beatriz Martin Jimenez will become the Lead for Sustainability and Impact on the global executive board in addition to her existing responsibilities, UBS added.

Both changes will take effect from March 1.

The changes come as UBS continues its integration of Credit Suisse, which UBS bought for 3 billion Swiss francs ($3.46 billion) in an emergency rescue last year.

Integrating the two arch rivals is a huge, multi-year task that will mean thousands of job losses in Switzerland and elsewhere and create a single financial institution with a balance sheet around double the size of the Swiss economy.

Since Ivanovic started his career at UBS in 1992 he has worked in all divisions of the bank as well as spent time at Credit Suisse and Morgan Stanley.

UBS Chief Executive Sergio Ermotti said Ivanovic's extensive experience and broad network across the firm made him "the ideal person to build on our strong foundation and progress our integration plans."

Jimenez, who joined UBS in 2012, has held key business and finance roles including Investment Bank Chief of Staff and Chief Operating Officer, Group Treasurer, and Group Head Transformation, said UBS.

The bank added that Jimenez has been closely involved with the firm's culture-building activities.