“Were dysfunction in this market to continue or worsen, there would be a material risk to UK financial stability,” the BoE said. “This would lead to an unwarranted tightening of financing conditions and a reduction of the flow of credit to the real economy.”

It said the purchases were designed to restore orderly market conditions. “The purchases will be carried out on whatever scale is necessary to effect this outcome.”

Earlier today, 30-year British government bond yields rose above 5% for the first time since 2002, as a sharp sell-off triggered by last week’s government fiscal statement continued.

Following the BoE statement, 30-year yields dropped around 20 basis points on the day.

The BoE said it was keeping its goal to reduce its £838 billion (US$892 billion) of gilt holdings by £80 billion over the next year, but would postpone the start of sales – due to begin next week – because of the market conditions.

The BoE said it would sell back the gilts it buys once market conditions had stabilised, and that Britain’s finance ministry had agreed to indemnify it against any losses.

“These purchases will be strictly time limited. They are intended to tackle a specific problem in the long-dated government bond market,” it added.