Azerbaijan’s leader on Monday accused Moscow of carrying out a “cover up” over a passenger jet crash last month that claimed 38 lives, as relations sour between the two neighbors.

Brazil’s air force says several of its investigators are working with colleagues from three other nations to analyze data from the Azerbaijani airliner that crashed in Kazakhstan on Dec. 25, killing 38 people.

SAO PAULO (Reuters) - The extraction of flight data from the Brazilian-made Azerbaijan Airlines plane that crashed in Kazakhstan last month was completed at a lab run by Brazil's air force, according to a statement released by the entity on Monday. The data from the Embraer plane was sent to the Kazakhstan authority investigating the crash.

In the crash’s aftermath, Azerbaijan has unleashed rare and stinging criticism of Russia, with the country’s president saying Moscow’s response has caused “surprise, regret and rightful indignation.”

Azerbaijani, Russia, Kazakhstan and Brazil are currently working together to investigate a horrific recent plane crash.

Indonesia on Monday officially joined the BRICS bloc of developing nations, marking a significant expansion of the group's global influence.

Flight records for the plane made by Brazil's Embraer that crashed last week in Kazakhstan are headed to the South American country so the data can be extracted, the Brazilian Air Force said in a statement on Monday.