The Egyptian airline whose plane crashed on Saturday was banned from flying to Switzerland because of safety concerns, Swiss officials say.
Egyptian and French rescuers are taking part in the search
Shortcomings were detected during a routine check at Zurich airport in October 2002, a Swiss aviation authority spokeswoman said.
A Boeing 737 belonging to Flash Airlines crashed into the Red Sea killing all 148 people on board.
Egypt says evidence points to technical failure as the cause of the crash.
The hunt for bodies continued on Sunday as Egyptian police closed off waters around the resort of Sharm el-Sheikh where the plane came down.
The wreckage, including the plane's two flight recorders, is thought to lie at least 1,000 metres beneath the sea.
Most of the dead were French tourists on their way back home.
The French Government has sent special equipment, including a robot submarine, to help the Egyptian recovery operation.
A team of DNA experts to help identify bodies is also going to Egypt.
Flash Airlines has two planes and it is not known if the plane that crashed was the one checked in Switzerland a year ago.
A spokeswoman for the Swiss Federal Office for Civil Aviation, Celestine Perissinotto, said she could not go into specific details but "it concerned violations of the regulations of the International Civil Aviation Organisation."
The failings were sufficient to warrant an immediate ban, she said.
A Flash Airlines plane on its way to Paris was allowed to make an emergency landing in Geneva last year, apparently because of bad weather.
The Swiss authorities demanded a full explanation of this incident from the airline but say the answer they received was "insufficient".
However, Egyptian Aviation Minister Ahmed Shafiq called the Swiss charge "baseless", the Associated Press reported.
Private Egyptian charter airline
Operates two Boeing 737-300s - both manufactured in 1993
Planes equipped with the latest navigational instruments, company says
Pilots have minimum of 5,000 hours flying time, company says
"If they have any proof, they have to submit it," he said.
Ms Perissinotto said that their report on Flash Airlines had been given to the Egyptian authorities but "since then we have had no reaction."
Other European countries, including France, had also been informed of their findings, she said.
Flash Airlines has said the aircraft was only 10 years old, was regularly serviced in Norway, and captained by a pilot with more than 5,000 hours of flying experience.
The company's chief pilot, Hassan Mounir, told AP that their planes were well maintained.
The Egyptian authorities have said the crash was an accident apparently caused by a mechanical problem.
Mr Shafiq said the Boeing 737 had climbed to more than a 1,000 metres (3,000 feet), veered off course and plunged within seconds into the Red Sea.
There was no distress call from the plane to the control tower.
The French have sent a minister to oversee the repatriation of the bodies that are brought to the surface.
Whole families are said to have perished while many children are among the dead.
Sharm el-Sheikh's hospital is the focus of anger as relatives of the aircraft's Egyptian crew demand to see the remains of their loved ones.
"They tell us there are only pieces of flesh placed inside and that we will not be able to identify anyone," one of the relatives, Hatem al-Qaliubi told AFP news agency.
There were 135 passengers - 133 French, one Moroccan and one Japanese - and 13 Egyptian crew members on the flight, which was on its way to Cairo for a stopover and crew change before heading on to Paris
French Prime Minister Jean-Pierre Raffarin visited the distraught relatives in Paris.
"I am personally overwhelmed by this tragedy and the whole nation is touched by this dramatic accident," said Mr Raffarin.
The crash comes amid increased alerts about possible terrorist threats that have led to tightened security and cancelled flights around the world.
Sharm el-Sheikh is a popular Red Sea tourist resort that also often plays host to political and economic summits.
Tourism is Egypt's main foreign currency earner, producing about $4bn a year and accounting for 11% of GDP.