Olusegun Obasanjo described the situation as "grave" and ordered an investigation into the cause of the blaze, Radio Nigeria reported late on Saturday.
The Nigerian president, who was on a state visit to Indonesia at the time of the incident, also called for increased protection of his country’s vast web of oil pipelines, the radio said.
The report said he would visit the site later on Sunday.
But Nigerians said little could keep poor villagers from rupturing pipelines that are ubiquitous across the south of Nigeria, saying the allure of free fuel outweighs the well-known danger.
Hakim Bolaji, 32, a boat driver who plies the swamps, said: "This has been going on for a long time, those people were just unlucky they caught fire this time.
"People are making so much money from selling stolen petrol that I'm sure they'll come back."
Obasanjo's order for greater security comes as militants in the oil region have stepped up attacks on pipelines and other petroleum-industry infrastructure in Africa's leading crude producer.
The militants are demanding more local control of the region's oil wealth.
"People are making so much money from selling stolen petrol that I'm sure they'll come back"
a boat driver in south Nigeria
The arson attacks have caused cuts in production by a quarter and sent crude prices soaring.
But there was no sign that Friday's fire on a ruptured pipeline was sabotage and police officials said they assumed villagers had ruptured it to steal fuel.
They said between 150 and 200 people died when the fuel ignited.
The Nigerian Red Cross also said on Sunday that it had stopped its rescue work as there had been no survivors.
Abiodun Orebiyi, the organisation's secretary-general, said: "We did not recover a single injured person or survivor at the site. They all died."
Rescue workers had aimed to finish collecting the dead for burial in mass graves by sundown on Saturday but at least 22 bodies floated in the tidal mangrove swamps many kilometres from the blast site at Ilado village.
"We did not recover a single injured person or survivor at the site. They all died"
Nigerian Red Cross
The state health commissioner in Lagos, Tola Kasali, said only after all bodies were buried, would a definitive death toll be given.
Kasali said on Friday that bodies in the region could pose a health risk to Nigeria's main city of Lagos, about 50km to the west, necessitating the quick and anonymous burial of the dead.
The blaze took place far from the centre of the fishing village of Ilado, and it was unclear if there were witnesses. Boatmen said they heard an explosion before dawn and saw the glow of flames.
The pipeline was run by Nigeria's state oil company and was used to transport gasoline across the country for national consumption.
The impoverished people of Nigeria often tap pipelines to get fuel for cooking or to re-sell on the black market.
More than 1,000 people in Nigeria have died in recent years when fuel they were pilfering caught fire.
In 2004, a pipeline exploded near Lagos as thieves tried to siphon fuel, killing as many as 50. A 1998 pipeline blast killed more than 700 in southern Nigeria.
Nigeria, which normally pumps 2.5 million barrels of crude a day, is Africa's largest producer and the fifth-largest source of imports to the US.
Despite the great wealth of Nigeria's natural resources, most of the country's 130 million people remain deeply poor.