Nigerians massed at polling stations on Saturday for what they hope will be their first credible presidential election for decades.

Despite two explosions hitting the troubled northeastern city of Maiduguri and blamed on a radical Islamist sect, there appeared to have been an orderly start to Election Day across most of the country.

"There is a heavy security presence all over town to ensure that people going to vote are safe," said Maiduguri's police spokesman Mai Mamman.

The first bomb exploded without causing any damage and the second blast shattered the windscreen of a car, but no other damage or casualties were reported.

Elsewhere in the country, supporters of all the parties appeared keen to vote.

"People are coming out massively," said Ogbu Titus, a school teacher on the outskirts of the capital, Abuja.

Former Canadian Prime Minister Joe Clark was leading a foreign observer team.

"Things seem to be quite orderly," he said. "Marterials seem to have been delivered on time."

Incumbent expected to win

Incumbent Goodluck Jonathan is the favorite to win, despite a poor performance by his People's Democratic Party (PDP) in last week's parliamentary and senate elections.

Jonathan was praised for appointing Professor Attahiru Jega, a man seen as having credibility, as the head of the election commission.

Last weekend's vote was largely viewed as free and fair, despite a weeklong delay due to organizational problems.

In Nigeria's half century of independence, the former British colony has been governed mostly by the military, infamous for its human rights abuses, corruption and suppression of publicly expressed opinions.

Tough challenges ahead

Whoever wins the presidential ballot will face some tough challenges. With a fast-growing population estimated at over 150 million and made up of diverse ethnic groups and religious communities, conflicts are frequent and often violent.

In the predominately Muslim north, radical groups have claimed responsibility for terror attacks on Christian civilians and the police because of their alleged “westernization,” which they claim is eroding Islamic culture.

The predominately Christian south controls the oil industry, the country's main source of income, but even here there are security problems, with militant groups regularly carrying out acts of sabotage, kidnappings and bomb attacks against oil installations. Oil accounts for over 70 percent of Nigeria's revenue.

Jonathan, who was sworn in as president on May 6, 2010, a day after his predecessor Umaru Yar'Adua died, comes from the south and has vowed to fight corruption and implement electoral reforms.

His campaign was controversial due to an informal pact with his PDP which stipulated that power should rotate between Muslim north and Christian south every two terms - a pattern his nomination breaks.

Jonathan's main challengers include former anti-corruption czar Nuhu Ribadu and former military ruler Muhammadu Buhari - both from the north.

Author: Gregg Benzow (AP, dpa,Reuters)
Editor: Toma Tasovac