BERLIN (AP) _ Prosecutors said Monday they proved Syria aided a terrorist bombing in West Berlin and demanded that the two Palestinian defendants receive stiff sentences to keep the city from becoming a battleground for the Middle East.

The West Berlin court hearing the case said it would issue a verdict Wednesday in the trial of Farouk Salameh, 39, and Ahmed Nawar Hasi, 35, who are accused of attempted murder and arms violations in the March 29 attack on the German-Arab Friendship Society. The bombing injured nine people.

''We cannot allow Berlin to become a battleground for the Middle East,'' prosecutor Detlev Mehlis told the court.

''Tough sentences are a weapon in the struggle against terrorism. Mild sentences will only lead to further terrorist activity,'' he said.

Prosecutors said the evidence at the trial proved ''beyond doubt'' that the bombing attack was carried out by the two defendants and was planned by Nezar Hindawi, Hasi's brother, with the help of Syrian officials.

Testimony has ''made clear the role of the fanatic Hindawi and his Syrian backers,'' Mehlis told the court. He said it was unclear ''which level of Syrian authorities'' were involved.

Both defendants remained silent throughout the lengthy summations.

When asked if he had any final comment, Hasi said, ''We carried out this action in the name of the Jordanian Revolutionary Movement,'' a reference to the terrorist group Hindawi wanted to build.

Hindawi, a Jordanian citizen, was sentenced to 45 years in prison by a London court last month for trying to blow up an Israeli jetliner at Heathrow Airport.

Mehlis asked the court to give Hasi a 14-year sentence and Salameh a 13- year prison term. Both defendents face a maximum penalty of 15 years.

''They (the defendants) showed no remorse throughout this entire trial,'' Mehlis said. ''All those who believe they can commit crimes such as these must be shown that our society will not tolerate it,'' he said.

Defense attorneys claimed their defendants were not professional terrorists and were often naive. The attorneys blamed the attack on Hindawi.

''We should make clear that neither of these two (defendants) are professional terrorists,'' Hasi's attorney, Gisela Kihn, told the court.

She said Hasi and Salameh were talked into the attack by Hindawi.

Hasi ''stood under the influence of Hindawi,'' Mrs. Kihn said. ''He held him in high esteem. He was in fact psychologically dependent on his brother.''

In his summation, prosecutor Joachim Lawatsch said testimony proved Hindawi traveled to Tripoli, Libya, in July 1985 to seek backing for a terrorist group he wanted to build in Europe.

When he failed to win Libyan support, Hindawi traveled to Damascus with Salameh in January, Lawatsch said.

In testimony presented at the trial last week, Salameh said Hindawi met in Damascus with Haitam Saed, who was identified as a ranking Syrian intelligence officer.

Hasi, in a pre-trial statement, said he had picked up the explosives used in the attack from the Syrian Embassy in East Berlin.

Western governments have closely monitored the trial for evidence of Syrian involvement in terrorism. West German officials have said the trial's outcome will play a role in Syrian-German relations.

Britain broke relations with Syria after Hindawi was convicted in the attempted bombing of the Israeli jetliner.