The president of the Spanish football federation Luis Rubiales said on Friday he will do "everything humanly possible" to ensure Spain hosts its four Euro 2021 games this summer.
Bilbao is due to host three group games and a match in the last 16 but the possibility of supporters attending is in doubt after the regional government insisted on a number of strict health conditions.
If UEFA decide in a meeting on Monday that Bilbao cannot host games, Rubiales has suggested Seville could be an alternative option.
The city's La Cartuja stadium will stage a second Copa del Rey final in two weeks on Saturday after the same venue also held the final of the Spanish Super Cup in January.
"What is clear for us as a national team, and I would say as a country, is that it is essential we are able to host," said Rubiales in Seville on Friday, ahead of this year's Spanish cup final between Barcelona and Athletic Bilbao.
"It is true that there are serious difficulties in Bilbao and with this in mind, it is UEFA who has to decide."
Rubiales said it would be "disastrous" if the four games were transferred to another country.
He continued: "I am going to do everything humanly possible so that whatever is decided in the meeting on Monday does not harm Spain, so that our base remains in Spain and, of course, La Cartuja is a magnificent place."
UEFA has confirmed nine of the 12 original host cities expect to be able to have stadiums filled to at least 25 per cent capacity this summer.
The remaining three - Bilbao, Dublin and Munich - have been given until Monday to submit additional information on fans attending fixtures, before a final decision is made.