Sanaa, Yemen (CNN) -- Yemen's defense minister escaped an assassination attempt Tuesday when a suicide bomber attacked his convoy, the Yemeni government said.
A bomb-laden vehicle exploded at 11 a.m., targeting Gen. Mohammed Nasser Ahmed's convoy in Tawahi, Aden, along Yemen's southern coast, the Defense Ministry said.
The bomber was killed. Witnesses said two explosions were heard and that clashes followed for 10 minutes.
An Interior Ministry source, citing the suicide bombing and the clashes, said the attack bears the hallmarks of al Qaeda.
Sultan Khaled, a witness, said, "The explosions were powerful and the city saw hundreds of troops spreading quickly."
Within minutes of the attack, government troops had blocked all entrances into Aden and set up checkpoints.
In late August, senior security officials in Abyan province said Ahmed survived an assassination attempt when a roadside bomb exploded near his vehicle, killing two of his guards.
But an official in the defense minister's office at the time denied that the convoy was attacked.
A senior official in Abyan said then that the ministry may have denied that attack because it did not want Abyan to be seen as outside complete government control.
Tuesday's attack came as anti-government protests in Yemen continued to attract huge crowds.
President Ali Abdullah Saleh returned Friday from three months in Saudi Arabia, where he received medical treatment following an assassination attempt in June.
Tens of thousands took to the streets of Yemen's capital, Sanaa, on Monday.
"We are escalating, and soon we will march directly towards the presidential palace," said Tawakul Karman, a prominent revolutionist. "The will of the people is stronger today, and Saleh is already part of the past."
But at the United Nations in New York, Yemeni Foreign Minister Abu-Bark Al-Qirbi accused opposition powers on Tuesday of using the "tidal wave of change" that has swept across much of the Arab world this year "to prevent Yemen from achieving democratic change through elections."
Al-Qirbi cited unbridled population growth, poverty, drought and scarcity of water and oil -- which had been a primary source of income -- for the nation's high rates of youth unemployment.
He cited the opposition's refusal to endorse Saleh's 2006 re-election, after 27 years in power, as "the main reason for the upheaval that is taking place in Yemen."
In a televised address Sunday, Saleh blamed "terrorists" for recent deadly violence at anti-government protests. The motive of the "criminal terrorists," he said, is "to seize power and to steal the wealth of the country and to undermine stability."
Protesters insisted that Saleh was trying to buy himself more time in office with the remarks.
Scores of protesters have been reported killed by Yemeni forces in protests in recent days.
Saleh said his vice president has the authority to sign a proposal by the Gulf Cooperation Council that would result in early presidential elections.
The United States has called on Yemen to follow the council's proposal.
The United States, the United Nations and the European Union have called on Yemen to halt the violence and called on both sides to establish a peaceful transfer of power.