With help from the United States, the Nigerian government announced Monday it was investigating which banks and countries were housing billions of dollars in stolen Nigerian state revenues, a local newspaper reported. Much of the looted monies were linked to Nigeria’s corrupt oil sector, in which 250,000 barrels of crude oil were believed to be stolen each day.

Nigerian President Muhammadu Buhari and his administration have enlisted help from the international community, including U.S. President Barack Obama’s administration, to pinpoint and recover the missing funds. In recent weeks, Nigeria’s new president has moved to strengthen bilateral relations with the United States and to keep his campaign promise of tackling corruption.

“We are getting cooperation from the international community, including information on ships that take crude oil from Nigeria and change direction, or pour their contents into other ships midstream,” Buhari said Monday at the presidential villa in Abuja, the Premium Times newspaper reported. “Some monies were paid to individual accounts. We are identifying the financial intuitions and countries that are involved.”

Buhari asked Obama to help trace the stolen funds before meeting with the U.S. president at the White House in Washington last month. In the oil sector alone, $150 billion was believed to have been stolen, Bloomberg reported. The Nigerian leader met Monday with U.S. Rep. Darrell Issa, R-Calif., in Abuja to discuss the steps taken to confront corruption issues in Nigeria, where the bulk of government revenue comes from its oil sales.

“I have been assured that when we get all our documents together, the United States and other countries will treat our case with sympathy,” Buhari said Monday, Premium Times reported.

During his visit to Nigeria, Issa announced that the United States was ready to provide training to the West African country to aid its fight against the radical Islamist group Boko Haram, which has claimed thousands of lives in three African nations, the Associated Press reported.

“We look forward to helping you in many ways to end the Boko Haram insurgency and the theft of crude oil in the Gulf of Guinea,” Issa, the leader of a U.S. congressional delegation, said Monday, Premium Times reported.