Gatwick Airport says its only runway has been closed to all flights because of a "spillage."

A spokeswoman says flights were suspended after the spill at around 10:15 a.m. on Monday. Several flights due to land were circling the airport, which is located 30 miles (50 kilometers) south of London.

The airport did not say what substance had spilled, but media reports said oil had leaked from a jet on landing.

Gatwick said it hoped to reopen the runway "soon."