Malaysia Airlines said on Thursday it would no longer use the flight codes MH370 and MH371 "as a mark of respect" to the 239 people on board its missing Beijing-bound passenger jet.
The Kuala Lumpur-Beijing service -- formerly MH370 -- will now take on the code MH318, while the return route will switch from MH371 to MH319.
"As a mark of respect to the passengers and crew of MH370 on March 8, 2014, the MH370 and MH371 flight codes will be retired," the national carrier said in a statement.
The airline said the changes would take effect from Friday.
"There are no changes to the frequency of our services, and we will continue to operate double daily services to Beijing," the airline added.
"Our thoughts and prayers remain with the families of our colleagues and passengers of MH370."
The search for the Boeing 777 entered its sixth day Thursday with Chinese satellite images showing possible debris in the South China Sea -- but Vietnamese planes found no trace of the objects, an official said.
The search for the missing airliner now encompasses an area of nearly 27,000 nautical miles (more than 90,000 square kilometres) -- roughly the size of Portugal.
Theories about the possible cause of the disappearance range from a catastrophic technical failure to a mid-air explosion, hijacking or even pilot suicide.