Libyan rebels painted the roofs of their vehicles bright pink on Friday not to be killed after a NATO air strike killed five fighters.
The strike hit a rebel tank column as it advanced on the disputed oil port of Brega on Thursday, causing a confused insurgent retreat back towards Ajdabiyah, gateway to the uprising's stronghold in Benghazi.
NATO, which is enforcing a no-fly zone in Libya, on Friday acknowledged that its planes were probably responsible for the incident, the second in a week.
Rebels heading west from Ajdabiyah towards the front against forces loyal to Muammar Gaddafi said the paint on their vehicle roofs was to avoid more fire.
Another NATO strike last week killed 13 rebels, including ambulance staff, on the outskirts of Brega.
"Twice, they've hit us by accident now," grumbled Belgassim Awamy, a rebel volunteer near the western entrance of Ajdabiyah.
"NATO is an alliance against the Libyan people," said Alaa Senudry, another rebel standing nearby.