LONDON: British 10-year government bond yields sank to their lowest in just over three months on Monday as investors sought safe assets in the face of growing concern about whether Prime Minister Theresa May can secure parliament's backing for her Brexit plan.

Ten-year yields dropped to 1.307 percent at 1722 GMT, their lowest since Aug. 24 and 6 basis points down on Friday's close, shrugging off a jump in share prices after the weekend's G20 summit that pinned down other European bonds.

The yield premium that gilts offer over 10-year Bunds  tightened to as little as 100.0 basis points, the lowest since Nov. 19.

Gilts typically rally - and their yields fall - when Brexit worries mount, as was the case on Monday when sterling fell to its lowest in five weeks against the U.S. dollar.

May faces an uphill battle to win parliamentary support for her Brexit plan in a Dec. 11 vote. And despite May's insistence on Monday that she still expected to be in office in two weeks' time, some investors are braced for turmoil.

"Much will likely come down to the scale of Theresa May's defeat... Certainly, one cannot rule out a leadership challenge or another election, with all the associated risks for markets," David Owen, chief European economist at U.S. investment bank Jefferies, wrote to clients on Monday.

But last week the Bank of England warned investors not to assume it would cut interest rates in response to a "disorderly" no-deal Brexit next March, as that could prove inflationary if businesses' struggled to maintain efficient supply chains.

Under a worst-case Brexit scenario, the BoE said its interest rates could rise as high as 5.5 percent, from a current level of 0.75 percent, as inflation spiked higher - a combination which would hammer gilt prices.