Since returning from Ghana, Nigerian President Muhammadu Buhari has been looking into reports that Nigerian crude oil firms may be scheming with Ghanaian oil companies to steal crude from Nigeria. During his one-day official visit to Ghana, Buhari said Monday he had received reports that Nigerian crude oil was entering Ghana’s industry, according to Nigerian newspaper Daily Trust.

"We are going to pursue this information and find out if it is legally done. We will try to get to the bottom of it and prosecute the companies or those persons who are involved," he said in Ghana’s capital city of Accra.

Buhari met with his Ghanaian counterpart, President John Dramani Mahama, for talks on bilateral relations, regional security, trade and other common issues Monday. But Buhari apparently had another agenda also atop the list: to persuade Mahama to track down and recover stolen Nigerian oil money suspected of being lodged in Ghanaian banks and real estate businesses. Over $1 billion of the Nigerian government’s looted oil funds is believed to have made its way into Ghana, which is facing a sinking economy despite the promise of an oil windfall, according to Ghanaian newspaper the New Statesmen.

Muhammadu Buhari President of Nigeria Muhammadu Buhari walks down the steps of his aircraft following his arrival at the airport in Yaounde, Cameroon, on July 29, 2015. Buhari visited his counterpart in Ghana Sept. 7, 2015, where he apparently received reports that Nigerian crude oil was entering Ghana's industry. Photo: Reinnier KAZE/AFP/Getty Images

Buhari, who took office May 29 after being elected on promises to tackle corruption, said his administration will retrieve what he called “mind-boggling” sums of money stolen from Nigeria’s opaque oil sector. Apart from seeking assistance from the international community, Buhari has not specified how his government will fulfill this task.

"250,000 barrels per day of Nigerian crude are being stolen and people sell and put the money into individual accounts," Buhari said in July, according to Reuters. "I assure you that we will trace and repatriate such money and use the documents to prosecute them.”

The United States has said it will offer its far-reaching powers to help oil-rich Nigeria trace billions of dollars in stolen assets. The lucrative oil sector provides the Nigerian government with about 70 percent of its revenue, and tumbling crude prices in the past year have hit Africa’s largest economy hard, Reuters reported.