India would not allow a UN investigator to join a probe of a crashed Air India jet that some safety experts had criticized for delays in analysis of crucial black box data, two senior sources familiar with the matter told Reuters.

The data from the recorders can be used to reconstruct the flight's final moments and determine the cause of the incident.

Investigators have begun analyzing data from the black boxes recovered from the Air India Boeing 787 jet that crashed earlier this month, killing 270 people.