Brazilian iron ore shipments rose 31% week on week to 8.33 million mt in the latest week, which was the highest level this year, according to data cited by Standard Bank Tuesday.

"We suspect Vale is letting go of some stockpiled materials ahead of the expected rainy season," Standard Bank strategist Melinda Moore said in a note.

Further, Vale's recent start-up of development at the Carajas N4WS mine may contribute to adding 10 million mt overall to 2015's output, the bank said.

Vale expects to ship 340 million mt in 2015, up from a 327 million mt target for 2014. The 2014 figure was revised early this month from an initial estimate of 321 million mt following better than expected volumes in the third quarter.

Anglo American has also started exports of pellet feed from its Minas Rio project.

Brazil in November exported around 26 million mt of iron ore, down from October's 31.78 million mt and the 30.9 million mt exported in November 2013, according to data from foreign trade agency Secex.