Three directors of the UK-based oil and gas group Encore Oil have sold more than 4m shares collectively in a sale that reduced their stakes by around 20%.Chief executive Alan Booth sold 1.55m shares at 143p each to net £2.2m. Eugene Whyms, finance director, sold 1.5m shares at 142p each to generate £2.1m and exploration director Graham Doré sold 1m ordinary shares at 142p each to net £1.4m.The group has licences in the UK Continental Shelf, including the North Sea, offshore Ireland and a production sharing contract offshore in Western Sahara. Encore's stock rose over 830% in 2010, with the majority of gains coming in the last seven months following the discovery of two potentially huge North Sea fields, Catcher and Cladhan.The potential at Catcher was underlined again on Tuesday when field operator Premier Oil reported a successful strike at its Varadero exploration well.Top Director BuysDaniel Stewart Securities (DAN) Director name: Mr Peter D SheaAmount purchased: 1,000,000 @ 1.35p Value: £13,500Top Director SellsCarnival (CCL) Director name: Mr Pier Luigi FoschiAmount sold: 200,000 @ 3,137.72p Value: £6,275,440Encore Oil (EO.) Director name: Mr Alan BoothAmount sold: 1,550,000 @ 143.00p Value: £2,216,500Encore Oil (EO.) Director name: Mr Eugene WhymsAmount sold: 1,500,000 @ 142.00p Value: £2,130,000Encore Oil (EO.) Director name: Mr Graham DoréAmount sold: 1,000,000 @ 142.00p Value: £1,420,000Condor Resources (CNR) Director name: Mr Klaus EckhofAmount sold: 9,000,000 @ 8.25p Value: £742,500Bango (BGO) Director name: Mr Lindsay C N BuryAmount sold: 295,000 @ 150.00p Value: £442,500Condor Resources (CNR) Director name: Mr Klaus EckhofAmount sold: 900,000 @ 7.00p Value: £63,000Condor Resources (CNR) Director name: Mr Klaus EckhofAmount sold: 260,000 @ 9.00p Value: £23,400