Some of the country's regions must diversify their tourism-dependent economy after the pandemic, Marques also told Reuters in an interview.
She expected a rebound of international visits to happen by the third quarter of 2021, depending on the success of a COVID-19 vaccine, but it could take until 2023 for those to return to pre-pandemic record levels.
Last year, Portugal had more than 16.4 million foreign visitors.
"We know it will be hard, it will take some time," Marques said, adding that Portugal sought to be among the first to benefit when people were allowed to travel freely again.
Tourism was crucial for Portugal's recovery from the 2010 economic and debt crisis and Marques is convinced it will help Portugal recover from the pandemic.
However, some regions rely too heavily on tourism, she said, calling for the development of other sectors there and a boosting of their international competitiveness.
Regions such as the southern Algarve, famous for its beaches and golf courses and particularly popular with British visitors, are among the most affected.
In Algarve, the tourism industry is not only suffering with the economic impact of the pandemic, which pushed the number of registered jobless up 134% to 24,088 last month from a year ago, but also from concerns about the implications of Brexit.
It is crucial not only to develop other sectors but to also attract more tourists from markets other than Britain to Algarve, Marques said.
"We need to diversify...but we will work to guarantee the Algarve continues to welcome all British people - no matter what happens with Brexit," Marques said.
The tourism industry contributed about 15% to Portugal's gross domestic product in 2018, latest official data show.
Though the sector all but collapsed due to the pandemic, with revenues sliding nearly 65% between January and September, Marques said residents opting to spend their holidays closer to home have lent a helping hand to the sector.
"I believe domestic tourism is here to stay," she said.