San Francisco  - Alaska Airlines was forced to cancel more than 40 flights as an ash cloud caused by an eruption of the Kasatochi volcano in the Aleutian Islands drifted into flight paths between Alaska and the contiguous US, the company said Monday.

The central Aleutian volcano erupted Thursday sending up huge plumes of ash, which began interfering with flights on Sunday as air currents pushed them into flight lines.

Numerous flights between Alaska and west coast destinations such as Portland, San Francisco and Los Angeles were canceled, forcing thousands of travelers to spend the night at the airport.

Alaska Airlines said it was trying to reschedule the passengers and planned to resume normal operations later Monday. (dpa)