Shea said he had so far discussed the issue with Royal Dutch Shell and BP, respectively the world's second- and third-largest Western oil companies by market value.
Security measures

While most oil companies already have substantial security measures, Shea said they were also keen to receive help with intelligence.

Nato is also in talks with Qatar about how it could help to secure the Gulf state's large liquefied natural gas (LNG) facilities.

LNG is gas cooled to liquid and transported under pressure in tankers. LNG facilities are seen as a particular security risk because of the pressurised gas.

Nato is not yet in talks with Saudi Arabia but may be prepared to help there as well, Shea said.