It is still too soon to determine what caused the crash of a Russian airliner in Sinai last week, the Egyptian head of the committee investigating the crash said at a news conference in Cairo on Saturday afternoon.

The Russian airliner crashed in central Sinai last Saturday morning, around 23 minutes after taking off from Sharm El-Sheikh airport. All 224 people on board were killed.

Investigator Ayman El-Moqadem said that a noise was heard in the last second of a recording taken from the downed airliner's black boxes. Investigators from Egypt, Russia, France and Ireland are still in the process of investigating the sound's source, along with the other evidence. 

"Some parts of the wreckage are missing and it is hoped to locate them in the coming days," he said, adding that poor weather conditions had hindered efforts to access the wreckage. El-Moqadem did not specify a timeframe for the conclusion of investigations.

Many western media outlets had quoted anonymous sources pointing to a bomb blast as the cause of the crash.

However, El-Moqadem criticised this coverage, saying that "the committee was not provided with any information or evidence in this regard."

Responding to a press question, El-Moqadem said he didn't know if the stories which cited, in some cases, members of the investigating team who had asked to remain anonymous, were really quoting committee members or those close to the committee. 

He concluded by saying that the committee is "considering with great attention all possible scenarios for the cause of the accident."

El-Moqadem was the only committee member, out of 47 investigators, at the press conference.

According to Ahram Online's Lina El-Wardani, who attended the conference, around six chairs were laid out for committee representatives before the conference began, but the organisers later removed all chairs except El-Moqadem's seat. 

El-Moqadem said that other investigators had been invited to attend the conference.