Swedish police offered a $70,000 reward today for information leading to Olaf Palme's assassin, as they sought to defend themselves against local criticism of their handling of the case.

In a news conference, Stockholm Police Commissioner Hans Holmer sharply disputed Swedish press reports charging police mishandling of the investigation. "This case is a very tough one," Holmer said. "It will take us some time to solve it."

The offer of a half million Swedish crowns, the equivalent of $70,000, was an indication of the acknowledged lack of police progress since Palme was shot late Friday night. It was the first official reward ever offered in a Swedish crime case.

Police have described the killing as "professional," and are investigating known terrorist groups including Kurdish extremists and West Germany's Red Army Faction.

Holmer said on Swedish television that based on details of the assault, including the type of bullets and the close range from which the gunman fired, "I have come to the conclusion that (the attacker) is a professional in the underworld," The Associated Press reported.

The only new information Holmer disclosed today concerned the probability that a running man seen getting into a car a few blocks from the scene was the killer. He said police still were looking for the car, which he did not describe.

Holmer also said that Sweden has enlisted assistance from Interpol and law enforcement authorities in Western Europe and the United States. U.S. officials, he said, were helping in ballistics and general terrorist expertise.

Local confidence in the police probe appeared to have eroded by this morning, when the country's largest newspapers published extensive critical articles. Each pointed out inconsistencies in police progress reports and offered the results of their own investigations into how authorities had responded during the crucial first hours after the slaying.

According to Dagens Nyheter, Sweden's largest and most respected daily, at least 20 minutes passed between the first police receipt of reports that a shooting had taken place, and the arrival on the scene of more than a handful of uniformed officers. Palme, who had been walking with his wife, as he often did, had dismissed his personal security guards for the evening.

The newspaper reported that nearly two hours passed between Palme's slaying at around 11:30 p.m. Friday and police moves to close or monitor routes out of the city and the country. The killer, the reports implied, had ample time to escape.

Holmer acknowledged that police have no idea whether the assassin is still in Sweden. But he denied the initial delay in the police response, saying that department computers had registered seconds between the first call about the shooting and the dispatch of police cars that arrived at the scene within three minutes.

It is clear from all accounts that for some minutes after the shooting no one knew that the victim was Sweden's prime minister.

One of the questions raised today concerned the two bullets fired by the assailant, one of which hit Palme and exited his body, while the other grazed his wife. Police reported earlier only that a bullet had been "found" in the vicinity of the slaying. Following news reports yesterday and today, however, they acknowledged that neither bullet had been located in their own search. Both had been found lying on the ground by civilians. The second, fatal bullet was found after authorities had stopped looking on Sunday.

It also emerged that the "peculiar" bullets -- copper-tipped, metal piercing projectiles that Holmer said Sunday were unknown to police here, were available in Stockholm, where a local television reporter yesterday purchased some in a shop barely two blocks from the scene of the crime.

When asked about this, Holmer said today, "I said we hadn't seen them before. I told you we wanted help. You helped us, and now you are blaming us."