Spanish news agency EFE reported "government sources" told it Puigdemont was in Brussels.
The former president of the Catalan regional government, who was stripped of his powers by Madrid over the weekend amid the country's deepening constitutional crisis, could face jail time if convicted of charges of sedition, rebellion and misuse of public funds.
Reports on Saturday from Belgium suggested the country's immigration minister, Theo Francken -- a member of a Flemish nationalist party -- had said Puigdemont could seek asylum in Belgium.
A statement from the Catalan leadership is expected later.
Spain’s attorney general Jose Manuel Maza announced earlier on Monday he had officially lodged complaints in the Supreme Court and High Court against the Catalan leaders responsible for Friday’s declaration of independence.
They now face charges of rebellion, sedition and misappropriation of funds, which could lead to heavy prison sentences.
Many of the independence leaders, including Puigdemont, have also been fired from their positions by Spain’s central government, which is now in control of the region.
And despite separatist leaders saying they do not accept Spanish rule of the region, Monday was the first working day in which their dismissal has taken effect, and only one of the fired politicians went to his office, but left shortly after, according to Spanish media reports.
According to Spanish law, Deputy Prime Minister Soraya Saenz de Santamaria is now the official leader of Catalonia.