Australia Arrow Energy Ltd has opened its books to Royal Dutch Shell and PetroChina <0857.HK> for them to conduct due diligence for their joint takeover offer worth at least A$3.3 billion ($3.03 billion) sources said on Wednesday.

One of the sources said Arrow is expected to make a response on the offer within days. ($1=1.088 Australian Dollar) (Reporting by Fayen Wong; Editing by Michael Perry)