Nov 26 (Reuters) - Myanmar's ruling military threatened on Friday to arrest citizens who invest in bonds offered by a shadow government, warning of lengthy prison sentences for their involvement in what it called "terrorist" financing.

The National Unity Government (NUG), an alliance of pro-democracy groups, ethnic minority armies and remnants of the civilian government overthrown by the military, said this week it had raised $9.5 million in the first 24 hours of its bonds sale.

The NUG says the proceeds from the zero-interest bonds will fund its "revolution" against the military in response to its Feb. 1 military takeover and bloody suppression of protests. It has not said how the funds would be used.

Zaw Min Tun, the ruling military's spokesman, said the NUG has been outlawed as a "terrorist organisation", so those providing funding faced serious charges.

"Action can be taken under terrorism charges with heavy sentences for those financing the terrorist groups," he told a regular televised news conference

"If you buy the money bonds, it falls under that (provision)."

The bonds went on sale on Monday to mainly Myanmar nationals overseas in denominations of $100, $500, $1,000 and $5,000, with two-year tenures.

The NUG did not disclose how many buyers took part in the sale, which requires participants to transfer funds to an account in the Czech Republic.