NAIROBI (AFP) - Somali pirates have released the Kuwaiti crude oil tanker Zirku boarding 17 Pakistanis, 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 tankers 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.