The ban was initially set to be lifted at 2 pm in Germany, but reports from the Volcanic Ash Advisory Centre (VAAC) in London said weather conditions were not favourable for moving the ash from Iceland's Eyjafjallajokull volcano out of the region.
A spokesperson for DFS – which allowed six German airports to operate for a few hours on Sunday – said the situation would be reviewed at midday as more information becomes available.
Regional air traffic safety authority Eurocontrol reported that 5,000 flights took place in Europe on Sunday, down significantly from the normal 24,000 flights.
According to Eurocontrol, countries that have closed their airports include Belgium, parts of Croatia, the Czech Republic, Denmark, Estonia, Finland, parts of France, most of Germany, Hungary, Ireland, northern Italy, the Netherlands, parts of Norway, Poland, Romania, Serbia, Slovenia, Slovakia, Sweden, Switzerland, Ukraine and the UK.
Over the weekend Chancellor Angela Merkel and many other European leaders were forced to cancel their plans to attend the state burial of late Polish President Lech Kaczynski, who died in a plane crash along with dozens of others in Russia a week ago.
Meanwhile thousands of travellers have been stranded in airports across the region and airlines bleeding billions of euros due to the ban have begun to question whether safety calculations are sensible or accurate.