Britain was unsure about Japan’s claim to the Senkaku Islands in the early 1970s, according to declassified documents seen by Kyodo News at the National Archives in London.

Officials were unable to establish whether Japan, China or Taiwan had a rightful claim over the small group of uninhabited islands in the East China Sea that continue to drive their bitter territorial dispute.

The advice was against making any comment on the respective claims. This position is maintained today by the Foreign Office which, when asked by Kyodo News, said it “does not take a position on the underlying sovereignty issues” and called for the matter to be resolved “peacefully and by international law.”

Officials in the 1970s were looking into the issue after the discovery of oil and gas deposits near the islands raised competing sovereignty claims.

The Senkakus are situated close to Taiwan, China and the Ryukyus, a chain of islands that belong to Japan and include Okinawa.

In January 1895, Tokyo incorporated the islets into Japanese territory after, according to the Foreign Ministry, “carefully ascertaining that there had been no trace of control over the Senkaku Islands by another state prior to that period.”

However, China and Taiwan claim to have owned them long before the Japanese took administrative control. They refer to the Senkakus as Diaoyu and Tiaoyutai, respectively.

A paper on the subject written by the Foreign Office’s research department in 1971 stated that a thorough study of documents and correspondence had failed to establish which country could rightly claim ownership of the Senkakus.

It stated, “The islands were not, for example, referred to in the Sino-Japanese negotiations of 1879-1880 over the Ryukyu Islands, nor in the 1895 Treaty of Shimonoseki by which China ceded Taiwan to Japan.”

Jim Hoare, a retired diplomat who drafted the paper, said the fact that Japan did not incorporate the islands until January 1895 suggests they were never part of the Ryukyu Islands and were part of the planned takeover of Taiwan later in 1895.

If this was the case, then the islands were unlawfully acquired and should have formally been given up in the 1952 Sino-Japanese Peace Treaty concluded by Japan and Taiwan, he said.

Another document from the 1970s shows the difficulty in assessing the competing claims.

Brian Hitch, a British diplomat in Tokyo in the 1970s, argued in the document that Taiwan could have a legitimate claim, given its proximity to the tiny disputed isles. But he also said Tokyo could have a claim in the sense that the Senkakus could have been part of the Ryukyus, which were incorporated into Japan in 1879.

After World War II, the Senkaku Islands came under the administration of the United States as part of Okinawa, and thus reverted back to Japan in 1972. Japan continues to control and administer the islets.

Relations between China and Japan sunk to a new low in September 2012 when the Japanese government purchased almost all of the uninhabited islands it didn’t already own from a private Japanese owner to keep them out of the hands of Tokyo, which was trying to buy them under an initiative by nationalist then-Gov. Shintaro Ishihara.

After sending several government ships and planes to shadow the area, China in November set up an air defense identification zone over the Senkakus, drawing a protest from Tokyo and other nations.