Continuing its northward rally,Reliance Infrastructure,ended the day with a gain of 5.17 per cent at Rs 645.30 on the Bombay Stock Exchange. In intra-day session,the scrip rose by 6.99 per cent touching a high of Rs 656.50. On the National Stock Exchange,the Anil Ambani-led firm settled 4.84 per cent higher at Rs 643.50. Meanwhile,the BSE key index Sensex closed at 18,358.69,up 191.05 points from its previous close.