* Gunmen abducted Kamene Okonjo, 82 on Sunday
* Police hunt for kidnappers, motive unclear
* Call received making demands, may be hoax (Adds interviews with witnesses, colour, details)
By Tife Owolabi and Tim Cocks
OGWASHI-UKU/ABUJA, Dec 10 (Reuters) - The family of Nigeria's finance minister made an emotional appeal for kidnappers to free her 82-year-old mother on Monday, saying the elderly woman was in fragile health.
Kamene Okonjo, mother of Finance Minister Ngozi Okonjo-Iweala, was abducted from her home on Sunday in Nigeria's oil-producing Delta state where kidnapping is rife.
"Around lunch time yesterday, some gunmen came to the compound and forced the gate open and took my mother away. The family is upset and traumatised," the minister's younger brother Onyema Okonjo told Reuters at the house.
"To abduct a grandmother more than 80 years old is sad. We appeal to them to release her as soon as possible because her health condition is not good," Onyema added.
Other members of the family sat outside in the sweltering heat as dozens of people arrived to offer support. The compound was surrounded by police.
Police said someone purporting to be one of the kidnappers had phoned on Monday to make some demands, but it was impossible to say whether the call was genuine.
"We have to identify the source of the call ... Anybody can make spurious calls and demands," said Delta state police spokesman Sergie Ezegam, without giving details of who was contacted or what was demanded.
"We still don't know the reason for her abduction. What we know is that this is a crime, the woman's life is in danger and we are making frantic efforts to rescue her," he added.
Criminal gangs regularly kidnap people for ransom in Nigeria, but it is rare for them to target members of the political elite.
Minister Ngozi Okonjo-Iweala has received threats in the past, her special adviser Paul Nwabuikwu said on Sunday.
Her drive to reform a corrupt and closed economy has made the economist popular with Western powers and Nigerians hoping for change.
But the former World Bank director has also made enemies along the way, especially among fuel marketers benefiting from a corrupt state subsidy scheme.
News of the kidnapping came as Okonjo-Iweala was locked in negotiations with parliament over the budget. It was not clear whether the abduction would affect her schedule.
Delta state Governor Emmanuel Uduaghan told journalists he had ordered security forces to rescue her within 24 hours.
Abductions are most common in oil-producing areas like Delta state. The majority of people abducted are Nigerians, but foreign oil and construction workers have also been targets.
Abductions spiked during years of militancy in the Delta, until an amnesty in 2009, but they remain commonplace.
The father of Chelsea soccer club player John Obi Mikel was kidnapped in central Nigeria last year and later freed. Authorities declined to comment on how he was released. (Additional reporting by Anamesere Igboeroteonwu in Onitsha; Editing by Andrew Heavens)