April 8 (Reuters) - Australian oil producer Woodside Petroleum Ltd's agreed $28 billion merger with BHP Group's petroleum arm was in the best interest of its shareholders, audit firm KPMG said in an independent expert report on Friday.

KPMG said its assessment found the merged group would have an underlying value of between $37.24 billion and $42.30 billion.

Woodside also unanimously recommended its shareholders vote in favour of the merger. (Reporting by Shashwat Awasthi; editing by Uttaresh.V)