Spain's national debt rose to 72.1% of GDP in the first quarter, up from 63.6% in the same period last year, according to the Bank of Spain.
The government expects the national debt to reach 79.8% of GDP by the end of the year, a figure that does not include the impact of a eurozone loan of up to €100bn to ailing Spanish banks.
Ratings agency Moody's has warned that the loan "will materially worsen the government's debt position" and projected Spain's public deficit would hit 90% of GDP this year and continue rising through 2015.
Spain entered its second recession in three years during the first quarter and is struggling with a record jobless rate of 24.4%, the highest level in Europe.