The start of operations of Brazil's Sudeste port in Rio de Janeiro state, which is planned to play an important role in minerals and metals exports, has once again been delayed, this time because port operators are waiting for a navy permit, port operators said Thursday.

No date has been publicly set for the start of port operations.

"The final stage [to Porto Sudeste starts operation] is sea channel access authorization from the Brazilian Navy," port operators said in a statement. "Upon necessary approvals Porto Sudeste will be ready for first shipment."

A Brazilian Navy spokesman did not respond to a query for comment.

Mineracao Usiminas (Musa), the mining arm of Brazilian steelmaker Usiminas, intends to resume iron ore exports as soon as Sudeste port receives the last permit to kick off operations, a source at the company said Thursday.

Musa has a take-or-pay agreement of $12.63/mt with port operators.

"Once the port informs the start-up date, Musa will begin the transport of ore to the port area," he said, adding it is possible to stockpile enough ore for a vessel in three days.

Musa expects to export at least 8 million mt of iron ore in 2015. The company halted exports in the third quarter of 2014 due to the lack of port availability elsewhere.

Usiminas in November received official notice from the port owners slating the beginning of its operations for January 1. However, the start was delayed indefinitely, following several start-up delays since the first deadline in 2012.

Originally part of Brazilian mining company MMX, now under bankruptcy protection, the port had 65% of its shares sold to Dutch commodities trading company Trafigura and Abu Dhabi's Mubadala Development sovereign fund in February 2014.