ISLAMABAD, Pakistan — Police arrested two more suspects Thursday in the suicide attack that killed opposition leader Benazir Bhutto, and thousands of her followers gathered at her tomb to mark the end of mourning for her and launch her party's campaign for this month's parliamentary election.
Interior Ministry spokesman Javed Iqbal Cheema said the two suspects were picked up in Rawalpindi, where Bhutto died in a gun and bomb attack Dec. 27. He declined to say whether the two men were key figures in the assassination, which threatened to plunge the nation into political chaos.
"I can't really comment on whether (the arrest) is important," Cheema told The Associated Press. "After the investigation, I will be in a position to say more."
Last month, police in northwestern Pakistan arrested two other suspects, including a 15-year-old boy who was alleged to have been part of a backup suicide squad assigned to kill Bhutto if the primary assassins failed.
The latest arrests were announced as a team of British detectives from Scotland Yard returned to Pakistan to report the findings of their investigation of the assassination. Their report is expected to shed light on exactly how Bhutto died _ amid confusion over whether she was killed by a gunshot or the impact of a suicide bombing.
British diplomats are expected to release a summary of the report Friday.
President Pervez Musharraf invited Scotland Yard to conduct its own inquiry after Bhutto supporters alleged the government may have been involved in her death. Musharraf rejected calls from Bhutto's party for an independent U.N. investigation.
U.S. and Pakistani officials believe the assassination was masterminded by Baitullah Mehsud, an al-Qaida-linked commander based in South Waziristan.
Mehsud leads Tehrik-e-Taliban Pakistan, a coalition of Islamic extremist groups fighting Pakistani forces in the lawless tribal area along the border with Afghanistan. On Wednesday, Mehsud's coalition announced an indefinite cease-fire with Pakistani forces.
Bhutto's slaying triggered nationwide riots that caused billions of dollars in damage and the deaths of at least 40 people. That prompted the government to postpone parliamentary elections for six weeks until Feb. 18.
The balloting is aimed at restoring civilian government after eight years of military rule. Musharraf was re-elected president in October but needs a strong majority in parliament to fend off growing demands for his impeachment.
Although the stakes are high, there has been little sign of public enthusiasm for the election. Campaigning virtually stopped after Bhutto's death, in part out of respect for the traditional 40-day mourning period and also over fears that Islamic extremists will attack large public gatherings.
However, Bhutto's Pakistan Peoples Party said it was ready to resume the campaign following the end of the mourning period. The party, now led by her husband, Asif Ali Zardari, plans a major rally Saturday.
About 10,000 mourners were at Bhutto's tomb in the southern province of Sindh to mark the end of the mourning period. Crowds filed inside the Bhutto family's grand marble mausoleum, where they showered petals on her grave. Weeping women recited passages from the Islamic holy book, the Quran.
Zardari, ringed by bodyguards, delivered a brief speech in which he described his wife as a martyr who fought to change "the system of exploitation" in impoverished Pakistan.
Bhutto had accused Musharraf's political allies of plotting to kill her, an allegation the government has denied.
"We will go out with a pledge to fight those who snatched away our leader. We will defeat them. We will vote them out," said Aisha Gul as she paid her respects at the tomb.
Associated Press correspondents Munir Ahmad in Islamabad and Zarar Khan in Sind province contributed to this report.