The four Arab states leading the boycott of Qatar said on Tuesday that their sanctions on Doha would remain in place until it meets their demands and that they would keep a close eye on the tiny Gulf monarchy's efforts to fight terrorism funding.

In a joint statement released in their state media, Saudi Arabia, the United Arab Emirates, Egypt and Bahrain said they appreciated U.S. efforts in fighting terrorism but that they would closely monitor Qatar's behaviour.

The United States and Qatar signed an agreement on Tuesday aimed at combating the financing of terrorism, as U.S. Secretary of State Rex Tillerson visited Doha to try to end a month-long rift between Western-allied Arab states

The four states imposed sanctions on Qatar last month, accusing it of financing militant groups and allying with the Gulf Arab states' arch-foe Iran, allegations Doha denies.