Business sentiment among Asian companies sank to an 11-year low in the second quarter, a survey has found, with some two-thirds of the firms polled flagging a worsening COVID-19 pandemic as the biggest risk over the next six months.

While the pandemic's initial impact was reflected in the March survey by Thomson Reuters and INSEAD, confidence during the June quarter fell by a third to 35 — only the second time the Asian Business Sentiment Index has slumped below 50 since the survey began in the second quarter of 2009.

A reading above 50 indicates a positive outlook. The last time the index showed a reading below that was in its debut quarter, when it hit 45.