Regarding Indian party invoicing another Indian party in USD

Hi, Request help on one query. Can an Indian company(1) who has got a project in foreign land subcontract it to another Indian firm(2) for delivery of one of the goods required for the project and issue the PO in USD instead of Indian currency. The Indian firm (2) has to deliver the goods directly to the foreign land. But the PO issued is by Indian company (1) to Indian firm (2). Would be great help if you could also share some reference of rbi which allows it.