An on-chip interconnect comprises control circuitry which responds to a burst read request received at an initiating requester interface, to control issuing of at least one read request to at least one target completer device via at least one target completer interface. For a chunking enabled burst read transaction, the control circuitry supports returning the requested data items to the initiating requester device in a number of data transfers, with an order of the data items in the data transfers permitted to differ from a default order and each data transfer specifying chunk identifying information identifying which portion of the data items is represented by returned data for that data transfer. For a data transfer returned to the initiating requester device based on data returned from one of a second subset of completer interfaces, the control circuitry generates the chunk identifying information to be specified by the given data transfer.