Hundreds of copies of Nigeria's 2016 budget have gone missing at the country's parliament, an MP who requested anonymity has told the BBC.
The senate was unable to start considering the proposed budget because of the missing documentation, he said.
The delay could worsen the country's economic crisis as it deals with the impact of plunging oil prices.
President Muhammadu Buhari delivered the hard copies of his first budget to both houses at the end of last month.
It detailed his plans to raise spending by 20% by borrowing heavily amid falling global oil prices.
The president, who came to power last May, also pledged to improve tax collection and invest in other industries including mining and agriculture to create more jobs.
Senate President Bukola Saraki held a closed door meeting with Mr Buhari late on Tuesday, but it is not clear if the issue of the missing documents was discussed.
The BBC understands that the copies of the budget for the lower house are not missing and will be distributed on Wednesday.
BBC Nigeria analyst Naziru Mikailu says this is an embarrassing development for the country's parliament and the government in general.
The MPs are already facing criticism for refusing to cut their salaries and allowances at the time the Africa's largest economy is facing its worst economic crisis in recent years.
Some opposition senators have reacted angrily to the news of the missing documents, accusing the government of being behind their disappearance, Nigeria's Premium Times newspaper reports.
But Mr Buhari's spokesman Garba Shehu denied the allegation, saying: "Once the budget is submitted, it ceases to be our property."
Both houses are expected to take about two months to consider the $31bn (£20.8bn) budget.