Lady Gaga has revealed that she was brought to tears by an email from Sam Smith.

The US star took to Twitter today (September 11) to post a somewhat cryptic tweet about a message she seemingly received from the Brit.

The 'Applause' singer suggested that Smith was looking for "advice" or "permission" on a matter.

Gaga wrote: "You're so special my baby. Your email made me cry @samsmithworld With the voice of an angel, u need no permission or advice. You're perfect."

The 'ARTPOP' icon meanwhile earlier took to Twitter to pay tribute to those affected by the 9/11 terrorist attacks.

She said: "Today we remember and honor all the lives + families ruined by the tragedy of 9/11. Practice love in their memory today #WeWillNeverForget."

Follow us: @Pressparty on Twitter / Pressparty on Facebook.

Watch Gaga and Smith in action below: