Attempts to secure a ceasefire in Libya have failed and the humanitarian crisis is worsening, the UN chief, Ban Ki-moon has said, while Muammar Gaddafi’s embattled regime freed four foreign journalists.

The UN Secretary General said that his special envoy to Libya, Abdul Illah al-Khatib, has been “working very hard” but he had no progress to report from efforts to sway Gaddafi to declare an immediate and verifiable ceasefire.

“In view of the deteriorating humanitarian situation, the crisis is getting worse,” Mr Ban warned.

He said he was very concerned about Misrata, which had been under siege from Gaddafi forces for more than two months and where hundreds have been killed. “The situation is getting very bad,” he said.

Mr Khatib travelled to Tripoli on Sunday where he held talks with regime officials on the need for a ceasefire and access to stricken Libyan cities, although he did not get to meet with Mr Gaddafi himself.

In Tripoli, four arrested journalists — two Americans, a Briton and a Spaniard — arrived at the Rixos Hotel late Wednesday after being freed by the authorities.

Mr Gaddafi is stubbornly refusing to call a halt to a conflict which erupted when he ordered his forces to put down pro-democracy protests launched on February 15 against his four-decade autocratic rule.