KUALA LUMPUR, March 14 -- A Chinese official on Friday called for rationality over the issue of the missing Malaysia Airlines jet which disappeared last Saturday morning with 239 people on board.

Guo Shaochun, who heads China's joint working group in charge of the missing Malaysia Airlines flight incident, told the media in Kuala Lumpur that they had noticed there were some reports and speculations that the missing flight MH370 had been hijacked or under terrorist attack. "Before the investigation result is given out by professional agencies of related countries, we will not comment on this," said Guo, who is the deputy head of the Department of Consular Affairs with the Chinese Foreign Ministry.

Guo meanwhile urged people to be rational and not believe in or spread rumors which may affect or disturb related investigations. "Whenever there is any progress, we will release it in time,"he said.

The working group sent by the Chinese government arrived in the Malaysian capital on Monday to handle the aftermath of vanished MH370 airliner and coordinate with Malaysia and other countries to investigate the incident.

Flight MH370, a Boeing 777-200ER, went missing suddenly on its way to Beijing last Saturday morning shortly after taking off from Kuala Lumpur. The plane was carrying 12 crew members and 227 passengers, including 154 Chinese.

Search and rescue operations by multiple nations have failed to find the trace of the plane as yet.