Somali pirates have released the Kuwaiti crude oil tanker Zirku, held since late March, after a \"massive\" ransom was paid, a piracy watchdog said Sunday. \"Sources close to the owners, diplomatic sources and local observers confirmed that the Somali pirates had let the UAE-flagged, Kuwaiti-owned oil tanker sail free after the ransom was paid,\" Ecoterra International said in a statement. Ecoterra, which monitors piracy off the coast of Somalia, said the \"massive\" ransom could set \"a new record for a vessel of that class\" but did not cite the amount. The tanker\'s 29 crew members, including 17 Pakistanis, are \"apparently all right\" after their relatively short time in captivity, Ecoterra said. The Zirku was seized on March 28 southeast of Oman by pirates firing rocket-propelled grenades and small arms from skiffs.