This study will evaluate the efficacy, safety and tolerability of AEB071 in the treatment of active, moderate to severe ulcerative colitis in patients who have failed conventional therapy using mesalamine or steroids

Inclusion Criteria:

• 18-75 years males and females
• Female subjects of childbearing potential must be using two methods of contraception
• Active, moderate to severe disease
• Poor response to or no toleration of conventional therapy (e.g. steroids, mesalamine)
• Good communication with the investigator, understanding and compliance with the requirements of the study and written informed consent

Exclusion Criteria:

• Allergy to the drug
• Very low or high body weight
• Ongoing treatment with specific other medication (e.g. antibiotics)
• Diagnosis of primary sclerosing cholangitis
• Renal impairment
• Toxic megacolon
• Presence or history of specific other diseases, cancer, cardiac abnormalities, abnormal laboratory findings
• History of alcohol or drug abuse
• Pregnant or breastfeeding women
• Positive HIV, Hepatitis B or Hepatitis C test result

Other protocol-defined inclusion/exclusion criteria do apply