American Express cardmembers and merchants will be the first to have exclusive access to Twitter's new advertising programme for small businesses, which is scheduled to launch in late March.

The card scheme says it will give $100 in free Twitter advertising to the first 10,000 eligible businesses that register for the programme. In return, small business owners must also sign up to follow American Express on Twitter.

Ed Gilligan, vice chairman of American Express, says: "This partnership with Twitter gives our small business owners access to a powerful tool for reaching and engaging existing and new customers."

The deal with Twitter marks AmEx's latest push into the social media space, and follows a spate of recent initiatives targeting consumers and merchants on FourSquare and Facebook.