Four ships carrying liquefied natural gas from Qatar have been diverted to supply Britain following a request for help from prime minister Boris Johnson, the Financial Times reported on Friday.

One vessel arrived at the South Hook terminal near Milford Haven on October 29, the second one arrived last Wednesday and the other two are still at sea. Together, these shipments account for about a third of Britain's normal monthly gas imports.

The British government hasn't purchased the gas – Qatar will sell it on the UK market – but the move is seen as part of an effort to secure Britain's supplies at a time of shortages and high prices.

According to a source quoted by the FT, Johnson asked for Qatar's help when he met the Emir at the UN General Assembly in September. They are said to have agreed to "deepen" the relationship between the two countries and the paper notes a series of other UK-Qatar contacts since then.

Qatar isn't one of Britain's main gas suppliers (most of its output goes to Asia) but according to the FT's sources, the British government is seeking a deal where Qatar would become a "supplier of last resort" – a sort of emergency back-up in the event of shortages.

No details have been given but it appears this would give Britain privileged access to Qatari gas, despite not being one of the Gulf state's major customers. How other customers might react to this, and what Qatar will expect by way of pay-back from Britain, remains to be seen.