11.   Relations are tense between Qatar and Bahrain because of their decades-old dispute over the Hawar islands and Fash al-Dibel rocks.

12.   Relations are tense between the Holy See and Moscow patriarchate, which accuses Catholic priests of proselytising in the Orthodox heartlands of Russia and Ukraine.

13.   Relations have been tense between Egypt and Sudan, with each side trading accusations.

14.   Relations were tense between Yemen and Saudi Arabia during the Gulf crisis when Riyadh accused Sanaa of backing Iraq.

15.   Relations have been tense between the European Union and Zimbabwe after the Harare government refused an EU request to allow election observers at presidential elections due in March.