OSLO (Reuters) - Norway said on Sunday it has sought an explanation from Moscow for a visit to a Norwegian island by Russia's deputy prime minister, who is banned from Norway in keeping with international sanctions against him over Ukraine.

Dmitry Rogozin is among a group of Russians who had sanctions imposed on them by the European Union and the United States after Russia annexed Crimea from Ukraine last year. Norway also adopted the sanctions, although it is not an EU member.

"We have earlier this spring clearly expressed to the Russian embassy in Oslo that people on the list are not wanted in Svalbard. It is therefore regrettable that Rogozin has been on Svalbard," a spokesman from Norway's Foreign Ministry said in a written comment to Reuters.

A representative of Rogozin declined to comment.

On Saturday Rogozin, who is also barred from U.S. travel, posted a picture on Twitter of himself in front of a signpost for Svalbard airport in the Norwegian island's main settlement Longyearbyen.

"We arrived in Longyearbyen in Spitsbergen," he wrote.

Norway has now asked for an explanation from the Russian authorities and will consider reinforcing entry procedures, including on Svalbard, the Ministry's spokesman said.

According to Rogozin's Twitter account he visited the village Barentsburg, a Russian mining town left over from the days of the Soviet Union, before heading further to the North Pole.

The islands of Svalbard is governed by a unique treaty, which grants Norway sovereignty over the islands, but signatories to the treaty, including Russia, retain equal rights to residence and commercial activities.

(Reporting by Stine Jacobsen in Oslo; Additional reporting by Polina Devitt in Moscow; Editing by Raissa Kasolowsky)