Nablus Mayor Bassam Shaka, who lost his legs when a bomb exploded in his car yesterday, accused Israeli secret police today of conspiring with ultranationalist Jewish settlers in an attempt to kill him.

Shaka, one of two West Bank mayors seriously injured by terrorist bombs yesterday, made his accusation in an interview in his hospital room as tensions grew in the Israeli-occupied Arab territory and police forced striking Arab shopkeepers to reopen their stores.

Shaka offered little evidence of official Israeli complicity in the bombing. He recounted a veiled threat reported to have been made by a local Israeli military governor and his suspicions that there were prowlers around his home the night before the bombing. He said he believed the prowlers could have been eavesdropping Israeli agents.

Israeli authorities have denied any official complicity but the accusations, repeated by other West Bank leaders in interviews, underscored the deeply rooted suspicion and mistrust of Israeli authorities by an increasingly militant Arab populace in the West Bank.

There have been no arrests in the bombings that maimed Shaka and Ramallah Mayor Karim Khalaf or in a third explosion in the automobile of another Arab mayor that blinded an Israeli demolitions expert.

Shaka said the attempt on his life was "a continuation of the Israeli government policy to evacuate the West Bank of its Palestinian leadership." The policy, he said, began with the May deportation of Hebron Mayor Fahd Kawsasme and Halhoul Mayor Mohammed Milhem.

Khalaf, in an interview at the Ramallah Hospital, blamed the militant Jewish settlement movement, Gush Emunim, for planting the bomb that blew off his left foot and badly mangled his right foot. He accused the Israeli government of tacity approving vengeance attacks on Arabs by Jewish vigilante groups.

Both mayors said the bombing attacks had strengthened their nationalist spirit, and they pledged to continue their struggle for Palestinian independence.

However, Bethlehem Mayor Elias Freij and his municipal council resigned today to protest the growing violence against Arabs in the West Bank, despite an appeal by other mayors to remain in office. Gaza Mayor Rashid Shawa and his council resigned yesterday.

Throughout the West Bank today, Arab shopkeepers attempted to stage a general strike, but Israeli Army troops forced many of them ot reopen, using bolt-cutters to break the locks of the shuttered shops.

Tensions were high in the West Bank, with painted Arabic slogans warning, "We will avenge Bassam Shaka and Karim Khalaf." Army units tightened security in the West Bank, putting up numerous roadblocks and searching cars.

One of those who blamed Israeli authorities for the terrorist attacks was Hekmat Masri, former speaker of the Jordanian parliament and a West Bank resident. He said, "Before, the Army was responsible for terrorism against Arabs. Now, there is a new, unofficial army that is linked to the government. They come in private cars, not Army cars. But we know who they are."

Several Ramallah residents said they noticed an unusually large Israeli Army presence in the town the night before the bombings, and they said they suspected that "some kind of operation" was imminent.

Shaka charged that when a high school student was shot to death last month in Anabta, near Nablus, after allegedly attacking a district military governor, the governor, Lt. Col. Mutsafi Shalom, told the dead youth's father, "I'm sorry. It would have been much better if it had been the son of Shaka."

Shaka said the night before the bombings, while he was entertaining guests in his garden, he noticed birds singing, as if they had been disturbed. "I investigated, but found nothing. It seemed to me it was the Israeli intelligence people listening," Shaka said.

Beyond these impressions, Shaka said, lies only his belief that planning the assassination attempt and rigging the bomb to detonate when his car's clutch pedal was depressed required knowledge of sophisticated demolition techniques not generally available to Israeli settlers.

Capt. Ishai Cohen, spokesmann for the occupation government, denied any official Israeli complicity. "I can't tell you whether it was Jews or Arabs. We don't know that. But, I can tell you that no security forces were involved," Cohen said.

West Bank military authorities stressed that they have no evidence to implicate either Jews or Arabs. But the state-owned Voice of Israel broadcast a studio interview with the former coordinator of the occupied territories, Gen. Abraham Orly, who suggested that the Palestine Liberation Organization was responsible.

"Histroically speaking, we have seen for ourselves that the PLO has executed personalities of the territories . . . In the Arab world, personal terrorism because of political differences is a normal weapon," Orly said.

Shaka appeared in extraordinarily high spirts less than 24 hours after his shattered legs were amputated. Although fed intravenously and connected to electronic monitoring systems, he smiled and joked amid wallposters bearing such slogans as, "If a patroit's legs are amputated, the people's legs stick deeper in the soil of Palestine."

Shaka said, "I have my heart. I have my brain. I have a just cause for which I struggle. I don't need legs."

But Shaka was bitter toward those he blames for the loss of his legs.

"We have an Arab proverb. The killer goes to the funeral of his victim and pretends to mourn," he said. "The military governor tried to enter my house to pay his condolences, and my family refused to let him in. They said, 'You are the murderer and you've come to pretend you are innocent?'"

Khalaf, although less severely wounded than Shaka, appeared to be in greater pain and was more heavily sedated. He blamed "settlers and Kahane groups" for his attack, referring to Rabbi Meir Kahane's ultranationalist Kach movement and his Jewish Defense League.

Khalaf said he had received threatening letters written in Hebrew, which he said he turned over to the military authorities "many months ago."

Both mayors, who are members of the militant National Guidance Committee, said they would return to their elective posts immediately upon recovering.

Meanwhile, a Paris journal, "Israel and Palestine," reporting a development that the Israeli Army censor had barred Israeli-based journalists from publishing, said that security forces on May 9 broke up a conspiracy by Jewish vigilantes to bomb the Al Aqsa mosque three days later to mark the 13th anniversary of the Israeli Army's capture of the Old City and East Jerusalem.

The vigilantes had stored a cache of 250 pounds of dynamite on the roof of a Jewish religious school in the Old City near the mosque, which is the third holiest shrine of Islam. Two Israeli soldiers were arrested, it was reported at the time, but the intended target did not become public until yesterday.