A sign at the one year anniversary of missing MH370. It will soon be the second anniversary the plane has gone missing on 8 March. Reuters

The search co-ordinators for missing MH370 Malaysia Airlines plane said search vessels are retracing their steps in certain areas following fears that they could have missed spotting the fuselage in earlier searches. This is the first time the Australian Transport Safety Bureau has admitted that the missing plane could have been missed during the search in the southern Indian Ocean floor.

The Boeing 777 was on a routine flight from Kuala Lumpur to Beijing with 230 passengers and crew on board when it disappeared on 8 March 2014. It will be two years since it has gone missing, with no clues as to location of the aircraft.

Other than a flaperon identified as belonging to the plane, being washed ashore the Reunion Island in July last here, the mystery surrounding the disappearance of the plane continues as its second year anniversary approaches.

The Australian Transport Safety Bureau which is coordinating the search for MH370, admitted that there is a possibility that the plane may have been missed in areas that had already been searched. The bureau's Chief Commissioner Martin Dolan told News Corp Australian Network that the challenging terrain and deep fissures in the sea bed meant that they were not always able to get a "good enough solar image."

He said: "We're taking another look because the areas where we haven't been certain are large enough to contain an aircraft - which is why we're going over them. The sea floor is very rugged and complex."

He reiterated optimism that the aircraft will be found before the operation is completed. An area "two-thirds the size of Tasmania" is still yet to be searched, Dolan said.

He however tempered the optimism with the following: "There was never a guarantee of success, but we still think there's a high likelihood of success before we finish [in June]. I still wake up every day thinking today could be the day."

Australia's Deputy Prime Minister Warren Truss had last year warned that the search for the aircraft could end in June, noting that no commitments had been made to search beyond the designated search zone. He said that the probability of "us finding the aircraft outside that square was low and therefore further search effort in the absence of new information was not likely to be cost-effective."

Joint Agency Coordination Centre chief Judith Zielke said that the centre had been preparing families since last April of the intention of not expanding the search beyond the current 120,000 square kilometer area. "No matter what we do that's an extremely difficult thing for the families to come to terms with and we will continue to hope that we're successful," she said.

A Chinese vessel will be heading for Australia to join in the search. This will take the total number of vessels involved in the search to four.

Dolan also noted that the ATSB is still awaiting the outcome of a French investigation into the flaperon found on Reunion Island. "At this stage, we've not heard anything from the French that would enable us to form a view about what position the flaperon was in when it separated from the aircraft which is the key question for us."

He added: It's quite possible we won't get anything definitive on that." In addition, Malaysia is also due to release another report on the second anniversary of the plane's disappearance.

"We're still waiting to understand what it is that they're intending to publish. That's up to them," Dolan added.