The company suffered an incident related to the control of temperature in the process of loading and sending out the vaccines, the minister said, adding the incident is now solved.
"They (vaccines) will be available tomorrow first thing in the morning in vaccination points," Illa said in an interview to Cadena SER radio station. Spain started vaccinating people on Sunday.
He expected around 70% of the country's population to be immunized by the end of the summer.
The delay in Spain comes after the vaccination campaign in Germany faced delays in several cities after temperature trackers showed that about 1,000 vaccine doses made by Pfizer and its partner BioNTech may have not been kept cold enough during shipment.
In a presentation this month, BioNTech had said that once removed from the freezer, the vaccine could be stored for up to five days at 2-8C and for up to two hours at temperatures up to 30C, prior to use.
The cool boxes designed by Pfizer are fitted with GPS trackers so the companies can deal with potential storage issues en route.
The vaccine, which uses new so-called mRNA technology, must be stored at ultra-low temperatures of about -70 degrees Celsius (-112°F) before being shipped to distribution centres in specially designed cool boxes filled with dry ice.
