A liquidity crunch at Qwest, the heavily indebted US telecom group, has forced it to draw on $4bn (€4.5bn) of emergency back-up loans amid accounting concerns.

Qwest is one of the biggest corporate bond market creditors in the world with about $19bn of bond outstanding and $25.7bn of total debt. But in the past few days it has been unable to find buyers for its commercial paper (CP), debt used by large corporations for routine short term borrowing.