Observers have said that security costs for the upcoming trial of the man accused of trying to blow up an airplane over Detroit last Christmas Day are raising concerns.

The Detroit News reported on Monday that experts say the costs to safeguard the city and defendant Umar Farouk Abdulmutallab during his trial could reach ten of millions of dollars, with uncertainty whether Detroit, the state of Michigan or the federal government should foot the bill.

The newspaper further said the Detroit trial of the 23-year-old Nigerian who allegedly tried to bring down Flight 253 with explosives hidden in his underwear will require sealing an international border, blocking downtown streets, keeping protesters at bay and securing buildings and infrastructure.

A spokesman for Detroit Mayor Dave Bing confirmed city police would be responsible for securing the streets around the courthouse should there be threats or concerns.

The News further reported that discussions between federal and local officials about who would pay for security were held at the time of Abdulmutallab's arraignment in January, spokesman Dan Lijana said, but he wouldn't say what came of those discussions. (With Inputs from Agencies)