A suicide bomber killed scores of people in Sana'a as servicemen rehearsed for a military parade near the presidential palace, a Yemeni police official said. The blast killed at least 75 people and injured about 120, according to the official, who declined to be identified in accordance with government policy. Al Arabiya television said 96 people died. No group immediately claimed responsibility. The attack took place in the presence of Defense Minister Mohammed Naser Ahmed and Chief of Staff Ahmed al-Ashwal, who were uninjured, the ministry said on its website. Yemen's army has been battling al-Qaeda militants as the government under President Abdurabuh Mansur Hadi fights to recapture cities in the southern province of Abyan. Government forces and allied fighters forced al-Qaeda militants to flee the suburbs outside the city of Lawdar on May 17. "There has been a call for al-Qaeda to strike at authorities in Sana'a in response to their offensive in the south," Theodore Karasik, director of research at the Dubai- based Institute for Near East and Gulf Military Analysis, said in a phone interview. The suicide bomber, wearing an army uniform, struck near the entrance to the palace, after which security forces closed access to the area and state television broadcast phone calls from officials and citizens denouncing the attack. The army was preparing for the National Day of Unification tomorrow which marks the creation of Yemen through the merger of the south and north in 1990. 'Heinous Crime' "This is a heinous crime that is meant to destroy the country and turn us into another Afghanistan," Ahmed al-Kamal, a soldier at the parade ground, said in an interview. "We will not give in to terrorism and will continue to celebrate our unity day." The explosion was "a bloody terrorist attack and shows the ugly face" of the attackers, said Najeeb Alsharabi, a 34 year- old blacksmith in an interview. "What is the crime of these slain soldiers?" Yemen, bordering Saudi Arabia and Oman at the southern tip of the Arabian Peninsula, is struggling to recover from protests that weakened the central government's authority and forced Ali Abdullah Saleh, who ruled the country for more than three decades, to cede power last year. Hadi was elected president in February. Oil Pipeline Attacks Yemen's army has fought separatist groups in the south and Shiite Muslim rebels in the north, as well as al-Qaeda. Attacks on the country's main oil pipeline have cost $2.5 billion in lost revenue, the oil and minerals minister, Hisham Sharaf, said last week. The conflict in Yemen has raised concern of a weakened central government, mirroring the situation in Somalia across the Gulf of Aden, where there's been no functioning administration since 1991. Somalia has become a staging post for pirates who attack merchant shipping lanes. Three U.S. Coast Guard trainers were attacked yesterday while driving near their hotel in the Red Sea port city of Hodiedah in western Yemen, an Interior Ministry official said, declining to be identified in accordance with government policy. One was wounded in the neck, the official said. "Reports of U.S. military trainers in Hodeidah are false," the U.S. Embassy in Sana'a said in a statement, without referring directly to Coast Guard personnel. White House counterterrorism adviser John Brennan visited on May 13 to discuss "extremist groups" and U.S. assistance with Yemeni officials, according to a U.S. Embassy statement at the time. Brennan's visit followed the disruption of a conspiracy by Yemen-based al-Qaeda in the Arabian Peninsula to build a potentially undetectable bomb in the month before the anniversary of Osama bin Laden's death.