Turnout in the Basque Country was similar to that in the last election
Nationalists have won the most votes in regional elections in Spain's Basque Country, but fallen short of a majority in parliament, final results show.
The results mean the nationalists, who have governed the Basque Country for 29 years, could be ousted from power by a coalition of non-nationalist parties.
In the north-western Galicia region, Spain's nationally-governing Socialists lost power to conservative opposition.
The polls were the first political test for Spain since it slid into recession.
In the Basque vote, the Basque Nationalist Party (PNV) won 30 seats in the 75-seat parliament, with the Socialists taking 24, final results showed.
The Socialists conceded defeat in the Galicia poll
Three other smaller nationalist parties - Aralar, Eusko Alkartasuna and Ezker Batua - which are expected to join a coalition with the PNV, won a further seven seats.
However, the conservative Popular Party won 13 seats and the small UPD won one seat, meaning a potential non-nationalist coalition would have one more seat than their rivals.
Never has a non-nationalist party led an elected government in the region, the BBC's Steve Kingstone reports from Spain. The PNV has been in power in the region for 29 years.
Much depends now on coalition talks which will take place over the coming days, our correspondent adds.
In Galicia, the governing coalition of the Socialists and the Galician Nationalist Bloc lost power to the Popular Party.
The PP secured a majority of 39 seats in the 75-member regional parliament.
The Socialists came second with 24 seats, while the BNG won 12 seats.
More than four million people were eligible to elect the regional parliaments in Galicia and the Basque Country.
In the Basque Country, the Socialists had focussed their campaign on the economy rather than issues of national identity.
They had run their election campaign saying that the real issue was jobs, rather than referendums and self-rule, our correspondent says.
The Socialists portrayed the leader of the current Basque government, Juan Jose Ibarretxe, as out of touch with real issues.
The PNV rejected those claims, saying that the Basque economy was doing so much better that the rest of Spain.
Unemployment is lower in the region than the national average, and Basque incomes are among the highest in Spain, our correspondent says.
Hours before polls opened, Basque police arrested a suspected member of the militant group Eta, who was believed to have been planning an imminent attack.
The 24-year-old had been under surveillance.
Officers later found what has been described as "bomb-making equipment" in an apartment in the town of Hernani, our correspondent says.
Eta had called the Basque election "anti-democratic" following a decision by Spain's Supreme Court to ban two separatist parties from fielding candidates.
Eta is blamed for more than 800 deaths in a 40-year campaign for an independent Basque homeland.