WITH little detail flowing out of Saudi Arabia after drone attacks on a refinery and oil field over the weekend, traders in London were noticeably nervous as they awaited further details.

The FTSE 100 closed the day down 46.05 points at 7,321.41 - a fall of 0.63% - but it was the oil prices that kept everyone interested.

A barrel of Brent Crude cost $67.43 as the markets closed, a rise of 12%, whilst a barrel of West Texas Intermediate Crude spiked 11.5% at $61.17.

The jump was smaller than the 20% rise seen in the first seconds of markets opening on Monday morning but, despite reassurances from the US and Saudi that they will tap into oil reserves to shore up markets, traders remained cautious.

As the day wore on, Saudi Arabia - which had previously said it could resume operations within days - said it would take weeks to fix.

The Aramco site refines around 50% of the country's crude oil - turning it into sweet crude - and 5% of the world's production.

Fiona Cincotta, market analyst at City Index, said: "There was only one subject that mattered today: oil. Traders have been unable to take their eyes off oil following attacks on Saudi's oil infrastructure over the weekend.

"As supply returns, we can expect the price of oil to start declining back towards $62, should geopolitical risks ease as well.

"However, with the US "locked and loaded" awaiting signs from Saudi Arabia that Iran was involved, tensions in the Middle East could get worse before they get better. Under these circumstances the price of oil could remain elevated for some time yet."

Oil-reliant companies, including airlines and cruise operators, suffered hardest from the fallout, while producers including BP and Shell enjoyed a boost to shares, with BP up 20.2p to 524.6p and Shell rising 43p to 2,322.5p.

In company news, Spire Healthcare failed to impress investors with shares down 3.3p at 121.8p, despite swinging to a first-half profit after it was buoyed by cost-cutting measures and increased numbers of NHS referrals.

The group, which owns 39 hospitals and treats NHS patients as well as those paying privately or through medical insurance, reported a £9.6 million pre-tax profit for the six months to June, rising from a £2.2m loss in the same period in 2018.

Troubled haulage firm Eddie Stobart Logistics warned that annual profits will be "significantly below" expectations after a poor first half of the year, due in part to delays on a major project.

The company is the target for a possible takeover by one of its biggest shareholders, DBAY Advisors. Shares remain suspended due to accounting problems.

UK defence giant Cobham won approval from 93% of shareholders to sell the business to US private equity firm Advent International for £4 billion.

Advent has offered 165p a share but, despite passing, shares closed the day up just 1.45p at 161.2p, with some investors remaining cautious that the Government could block the deal.

The biggest risers on the FTSE 100 were BP up 20.2p at 524.6p, BT up 5.8p at 177.22p, Royal Dutch Shell A up 48.5p at 2,331p, Royal Dutch Shell B up 43p at 2,322.5p, and Micro Focus up 20.6p at 1,147.6p.

The biggest fallers were Prudential down 53p at 1,480p, Evraz down 17.4p at 518p, Rolls-Royce down 26.2p at 805.6p, St James's Place down 28p at 1,002.5p, and CRH down 76p at 2,761p.