Actress Julia Roberts has denied reports suggesting she is pregnant with her fourth child.

The Erin Brockovich star hit headlines after photographs surfaced online last weekend (07-08Dec13) reportedly showing the actress trying to conceal her stomach with an oversized sweater.

She addressed the rumours during an appearance on U.S. late night show Late Show with David Letterman on Thursday (12Dec13).

When pal Letterman asked if there was "any chance" she was expecting, the actress replied, "No".

Roberts has three children with husband Daniel Moder - twins Hazel Patricia and Phinnaeus 'Finn' Walter, nine, and Henry, six.

But asked if she was interested in expanding her family, she added, "Oh sure!"