Gunmen seriously wounded an Army general here today in apparent reprisal for the assassination last night in Bilbao of a Basque extreme nationalist leader.

The double shootings highlighted Spain's continuing terrorist problem and appeared to undercut prospects for a negotiated cease-fire with the Basque guerrilla movement ETA.

Gen. Luis Roson was shot in the chest by two youths who approached his car and opened fire as it stopped at a traffic light in central Madrid. He underwent an emergency operation and his condition was described as serious. His driver, a soldier, was also severely injured.

Roson, 66, is a member of a prominent political family; a brother, Juan Jose Roson, is a former minister of the interior. The general held a desk job.

It was the first terrorist attack on a general since January, when ETA claimed responsibility for the fatal shooting in Madrid of Gen. Guillermo Quintana Lacaci. Police said Roson's attackers, who escaped in a waiting car, used ammunition of the type habitually employed by ETA.

The shooting appeared to be linked to the assassination the previous day of Dr. Santiago Brouard, a member of the governing council of Herri Batasuna, the coalition of extremist Basque parties that acts as the political front for ETA. Brouard, a pediatrician, was killed in his Bilbao office by two men described by police as professional killers.

The central government's delegate to the Basque region, Ramon Jauregui, said the assassination would have "extremely grave political consequences." Rioting broke out overnight in Bilbao, San Sebastian and elsewhere in the Basque country. Herri Batasuna ordered a general strike for Thursday.

Political sources here said the shootings had effectively undone progress on a carefully conceived grand strategy by the government to contain ETA. The strategy involved increased police action against the terrorists coupled with international, and particularly French, cooperation. The government was at the same time pursuing a policy of leniency and of individual pardons for ETA members who foreswore violence.

Parallel to this approach, the government reportedly has had discreet contacts with the ETA leadership aimed at negotiating a cease-fire. These reports, published by Spain's leading newspaper, El Pais, have been denied by government spokesmen. The sources said that whatever contacts the government might have had with ETA, the possibility of negotiations had now been cut short by the shootings.

Prime Minister Felipe Gonzalez said the assassination of Brouard was "a provocation against the policy of pacification." Brouard, 64, was an influential member of Herri Batasuna's leadership and his links with ETA dated back at least to 1973, when he chose temporary exile in France after police accused him of giving medical treatment to a wounded terrorist.

The widespread belief in the Basque country, among Herri Batasuna and pro-ETA sectors, is that Brouard was killed by a right-wing death squad called GAL that has been responsible for a number of attacks in the past year against ETA members who lived across the Spanish border in France. Brouard was the first leading Herri Batasuna politician to be assassinated.

The extreme nationalist sectors have charged that GAL was masterminded by Madrid -- a charge the government has denied. Government sources said an investigation had been launched in Bilbao to capture Brouard's killers.

The death of Brouard seems certain to strengthen the Herri Batasuna platform of opposition to Madrid's Socialist government. The revenge shooting of the general, in the view of Basque extremists, is likely to raise the prestige of the Marxist ETA.

Conservative opposition leader Manuel Fraga Iribarne said after seeing Roson, "Obscure contacts [with the terrorists] are not the way to solve the ETA problem."