The Emir of Qatar, Sheikh Tamim bin Hamad Al Thani, is expected to reject allegations that his country is funding Islamic State militants during a three-day state visit to Britain that began on Tuesday.

Sheikh Tamim's first official visit to Britain since becoming emir in 2013 will include talks with Prime Minister David Cameron and a meeting with Queen Elizabeth.

Qatar is one of the world's richest countries and has invested heavily in British firms and property. Among its investments are London's tallest building, the Shard, which was funded by the Qatari royal family, and the upmarket Harrods department store, which is owned by sovereign wealth fund Qatar Investment Authority.