The weaker-than-expected Chinese trade figures contributed to Anglo American falling 2 per cent or 23.3p to 998.7p and BHP Billiton dropping 47.5p to 1,416p.
Standard & Poor’s downgrade warning came as it lowered its iron ore price estimates for the next couple of years.
The FTSE 100 index, which set a new record on Friday amid relief over developments in debt-ridden Greece, fell 25.47 points to 7,064.3.
Insurance firm Aviva was one of the biggest risers in the top flight – up 6.5p to 561.5p – on the first day of trading for its shares following the completed £5.6 billion takeover of Friends Life.
Sentiment towards the insurer was helped by broker comment, with JP Morgan believing the company is better placed in the UK market as a result of the deal.
It reinstated Aviva at overweight and placed a target price of 622p.
Other stocks on the front foot included HSBC, which climbed 5.9p at 618p, and Royal Bank of Scotland with a rise of 4.3p to 353.2p.
Tesco was one of the biggest fallers, down 6.7p to 244.3p, amid reports that the supermarket is facing impairment charges as high as £3bn from its failing outlets when it posts its annual results next week.
Low-cost airline easyJet was 23p lower at 1,892p after it announced the recruitment of Andrew Findlay from car parts firm Halfords as its new chief financial officer.
Halfords shares were 8p cheaper at 463p as it said the search for a replacement was underway.