Seven Estonian cyclists were kidnapped by gunmen in late March after crossing the Syrian border with Lebanon.
A formerly unknown group calling itself the Renaissance and Reform Movement issued an e-mail statement to Lebanese media this week demanding an unspecified ransom and Lebanese authorities have expressed concern that Syria might be behind the abductions.
Michael Williams, the U.N. special envoy to Lebanon, met with Prime Minister-designate Najib Mikati to discuss efforts under way to free the Estonians.
Williams expressed his appreciation for Lebanese efforts to secure their release, adding that the detention of the Estonians did little for regional security.
"No purpose is served by their continued detention," he said in a statement.
Lebanese authorities have several suspects in custody in connection with the abductions. The ransom note added the Estonians were in good condition but declined to indicate where they were held.