JAKARTA (REUTERS) - Indonesia's central bank said on Thursday it ordered the suspension of export licenses of a number of small exporters who failed to report their foreign currency earnings.

A Bank Indonesia (BI) spokesman, Difi Johansyah, told Reuters that the central bank asked the customs office to suspend permits for violators, though he declined to name them or specify how many firms and what amount of export earnings were involved.

"Those exporters sanctioned are small firms and do not have a clear identification or address. Almost all big exporter firms are cooperating with the regulation," Mr Johansyah said.

The suspension of export licenses comes as analysts say BI is tightening loopholes to give it more control over the rupiah to ensure a weakening in the currency does not turn into a panicky tailspin.

The central bank spokesman said "We will maintain our efforts to implement the regulation. Bank Indonesia only asks exporters to record their forex in the domestic market. BI is not asking them to put the money in for a certain period or convert it into rupiah."

Some analysts have questioned whether the rule, which BI imposed in September 2011 to help it more precisely count the amount of onshore foreign currency, has much effect.

"(It) is not effective since BI only ask exporters to report and afterwards (exporters) can transfer the money out," said Bank Internasional Indonesia economist Juniman.