Safety inspectors have launched an investigation into why it took more than an hour for warning messages to be sent out about a large-scale fire at the Esso oil refinery in Rotterdam.

The blaze broke out at around 9.30pm on Monday, but the first NL alert message was issued at 10.29pm and was missing vital details such as the location of the fire. A more specific update was sent five minutes later.

The local safety board (Veiligheidsregio Rotterdam-Rijnmond) said it was reviewing its communications systems, NOS reported. The rijnmondveilig.nl website, which was supposed to carry updates on the state of the fire, went down for 45 minutes at the height of the incident.

The cause of the fire, which sent large quantities of smoke and soot into the atmosphere, has not yet been established. Local residents have been warned not to eat homegrown fruit or vegetables until tests have being carried out on soot particles that fell to the ground.

Esso has set up an information hotline for residents and said anybody whose property has been damaged would be compensated.