UPDATE 9-New Nigerian leader pledges electoral reform
* Jonathan must now appoint new vice president
* Thousands of mourners gather in Yar'Adua's home town
* Open race to succeed Yar'Adua in next polls
(Adds comment from ruling party, opposition)
By Randy Fabi and Felix Onuah
ABUJA, May 6 (Reuters) - Nigeria's new leader Goodluck Jonathan vowed on Thursday electoral reform and fighting graft would be top priorities as he steers the nation to its most fiercely contested polls since the end of military rule.
Jonathan was sworn in as head of state in Africa's most populous country following the death late on Wednesday of President Umaru Yar'Adua, who died peacefully aged 58 after a long battle with kidney and heart ailments.
"Our total commitment to good governance, electoral reform and the fight against corruption would be pursued with greater vigour," Jonathan said after taking the oath of office in front of ministers, state governors and ambassadors in Abuja.
Maintaining peace in the Niger Delta, the heartland of the OPEC member's 2 million barrels per day (bpd) oil industry, would also be a top priority, he said after being sworn in by Nigeria's Chief Justice Aloysius Katsina-Alu. Continued...