Several people have alerted me to an excellent military blog running out of the Netherlands run by utility enthusiasts.
Contributor Nils from Denmark (callsign DK8OK), posted an MP3 audio file monitored on 6877.0 kHz shortwave this morning (Sunday) at 09:00 UTC, in upper sideband mode (USB) with reduced carrier. The transmission is lightly jammed in Europe, difficult to know what reception is like just off the Libyan coast.
The voices were advising Libyan seamen to return to port and leave their ships. The (live?) announcements were in Arabic, English and French. I hear slightly different text to the one posted on the blog.
"Libyan sailors! Leave your position immediately and return to port. The Gadaffi regime forces are violating a United Nations Resolution number 1973... If you leave now and return to port no harm will come to you. Do not attempt to jam this transmission." Click here for Nils DK8OK audio file.
Looks like the broadcasts may come from an EC-130H Compass Call aircraft, which is equipped with radio transmitters on board the aircraft and whose mission is to "disrupt enemy command and control communications and limits adversary coordination essential for enemy force management". Being shortwave, there is no reason why the broadcasts could not originate from one the ships offshore. They don't need line of site for this work. So while we know that the psyops planes are in the region, this broadcasts to sailors at sea doesn't have to originate from the air.