Spain's daily coronavirus death toll shot up to 743 on Tuesday after falling for four straight days, lifting the total to 13,798, the health ministry said.
However, it emphasised that the rise was due to weekend deaths being tallied and that the overall "downward trend" is continuing.
The new figure represents a 5.7 percent increase over the 637 deaths recorded on Monday, the lowest number of fatalities since March 24 in the world's second hardest-hit country after Italy in terms of deaths.
The number of new infections also grew at a faster pace, rising 4.1 percent to 140,510, the health ministry said. The number of new cases had risen by 3.3 percent on Monday.
The "slight" rise was due largely to the fact that many deaths and new infections which occur over the weekend are only now being tallied, said Maria Jose Sierra of the health ministry's emergencies coordination unit.
"In reality the downward trend is what we continue to observe in the reports we have received in recent days," she told a daily news conference to discuss the figures.
The number of people in hospital intensive care units continues to fall, she added.
Spain had seen the number of new infections and death drop each day since it recorded a record 950 fatalities on Thursday.
But the percentage increase in the number of new deaths is far lower than the 32.63 percent leap recorded as recently as March 21.
Mari Angels Rodriguez, a nurse at the Hospital Josep Trueta hospital in Girona in northeastern Spain, said the volume of work in the intensive care unit had fallen "a lot".
"The collapse in the first few days was brutal, everyone was coming to emergency services, all the usual causes as well as all the possible cases of COVID-19," she said.
"What wears me out the most is seeing young and middle aged people, without chronic conditions, who arrive in moderate shape and quickly end up in the intensive care unit (ICU)."
"The other day a 17-year-old girl was admitted to hospital and the next day she was in the ICU. It is full of young people. Psychologically you are not ready for this," she added.
"It hits you the speed with which a patient gets seriously ill. When they start to get bad, it is like they are drowning, in half an hour they are intubated or are dead."