Tobacco, engineering and housebuilders helped FTSE 100 extend gains above the 7,000 mark on a day when the market shrugged off prevailing political uncertainty about a hung parliament as well as weak industrial output.At 16:18 BST, the FTSE 100 was up 0.87% or 61.35 points to 7076.71 with tobacco blue chips British American Tobacco (up 2.09%) and Imperial Tobacco (up 2.63%) leading the way in anticipation of higher yields over a largely positive trading session for the market.Goodwin (up 7.26%), Weir Group (up 0.60%) and Vitec Group (up 2.17%) led engineering stocks higher. UK-listed oilfield services firms generally performed well premised on the belief that the operational climate in the British oil and gas sector was stabilising.Housebuilders benefitted as Jefferies upgraded ratings for stocks across the sector, saying that companies have a "spring in their steps".The broker raised Bellway (up 1.59%), Bovis Homes (up 1.63%), Countrywide (up 5.67%), Crest Nicholson (2.98%), Redrow (up 1.69%), Taylor Wimpey (up 2.79%) and Zoopla (up 3.03%) from 'hold' to 'buy'. Barratt Developments (up 3.05%), Berkeley (up 1.07%) and Persimmon (up 0.98%) were lifted from 'underperform' to 'hold'.Going the other way, the mining sector endured a downbeat session as the iron ore market slump continued. The most active three-month iron ore futures contract for September delivery on the Dalian Commodity Exchange in China hit a low of 368 yuan ($59) per tonne; its lowest since the launch of the contract in October 2013.Friday's close marked the fourth consecutive weekly loss in wake of falling demand from steelmakers, oversupply and a stronger dollar. Meanwhile, iron ore spot markets also continued in the red. At the end of the latest session, the benchmark 62% grade iron ore for immediate delivery to Tianjin, China was trading at $47.80 per tonne, down 0.2% from its previous close of $47.90.Elsewhere, Glencore said it would be closing its Singapore coal sales desk in favour of consolidating its Australian business and cutting costs. Leading iron ore exporter Rio Tinto (down 1.00%), Vedanta Resources (down 3.71%), BHP Billiton (down 0.12%) Anglo American (0.63%) and Glencore (down 0.20%) were all in the red.General bearishness in the sector tool also took its toll on BlackRock World Mining Trust knocking 1.5% of its share value to 295.50p.Top Five Sectors:Tobacco 44,207.12 +960.68 +2.22%Industrial Engineering 9442.10 +146.30 +1.57%Household Goods & Home Construction 14,884.58 +225.72 +1.54%Pharmaceuticals & Biotechnology 14,544.36 +210.41 +1.47%Mobile Telecommunications 5,216.77 +68.59 +1.33%