DURBAN: Off-spinner Graeme Swann struck two early blow for England as South Africa set out in their quest to avoid defeat on the fourth day of the second Test against South Africa at Kingsmead on Tuesday.

South Africa, trailing by 232 runs on the first innings, were 37 for two at tea, still 195 short of avoiding an innings defeat.

Swann continued his uncanny knack of taking a wicket in his first over of an innings when he dismissed Ashwell Prince with his second ball.

He followed up two overs later by bowling Hashim Amla in the last over before tea.

Swann was brought on after Prince and South African captain Graeme Smith had taken the total to 27 in nine overs without any major alarms.

He had Prince caught for 16 by Ian Bell off bat and pad at silly mid-off. Amla made six before missing a drive against a ball which spun sharply to hit his off stump.

Bell earlier hit 141 as England made 575 for nine declared, adding 189 runs for the loss of four wickets on Tuesday.

Bell and Matt Prior (60) put on 112 for the sixth wicket in a partnership which wrecked South African hopes of making a breakthrough early in the day and ensuring that the deficit would be less than 100 runs.

Bell and Prior had no difficulty in seeing off Dale Steyn and Morne Morkel, South Africa's main strike bowlers, at the start of play.

With the pitch playing easily under an overcast sky, Smith was soon forced on the defensive.

Bell and Prior gradually increased the tempo and Prior seemed set to go on a major assault when he raised a 77-ball half-century with a six off left-arm spin bowler Paul Harris. He hit one more boundary but was then bowled by off-spinner JP Duminy when he chopped an attempted cut onto his stumps.

Bell, whose place as a number six batsmen had been questioned by several commentators because it left England with only four specialist bowlers, justified the confidence shown in him by the team management with a composed, confident innings.

After posting his fifty on Monday off 65 balls, Bell was more circumspect on Tuesday, reaching his ninth century off 172 deliveries when he went down the pitch and lofted Harris over mid-on for his eighth four. He also hit a six.

It was Bell's first Test century since he made 199 against South Africa at Lord's in July 2008.

England went on the attack immediately after lunch, adding 62 runs for the loss of three wickets in nine overs before Andrew Strauss declared.

England batsman Paul Collingwood, who made 91 on Monday, dislocated his left index finger during fielding practice before play. He was sent for X-rays which revealed no fracture. He did not field at the start of the South African second innings.