New Zealand bowled Bangladesh out for a record low of 70 as they cruised to a 75-run victory at cricket's World Twenty20 Saturday, maintaining their perfect record at the tournament.

Allrounder Grant Elliott took three wickets for 12 runs in his four overs while Ish Sodhi chipped in with three for 21 as Bangladesh's quest for a consolation win ended in tatters.

The Black Caps, who had already qualified for the tournament's semi-finals, had earlier made 145 for eight at Eden Gardens with Mustafizur Rahman taking five for 22.

But what had appeared to be a modest total soon proved to be too much for the Tigers who lost their leading batsman Tamim Iqbal in the second over, run out for just three.

Bangladesh were all at sea against New Zealand's quartet of slow bowlers and their top score came from tailender Shuvagata Hom who made 16. Only two others reached double figures.

After 11 overs they had made 45 for six and then had to sweat it out in the dressing-room after a floodlight failure brought a halt to procedings for more than 10 minutes.

After the resumption, they continued to find the Black Caps' bowlers pretty much unplayable and their innings only featured one six, a late blow from Rahman.

The total was the lowest for Bangladesh in any T20 international, with the record previously standing at 78.

It heaps more misery on a Bangladeshi team who failed to win any of their games at the tournament and suffered an agonising one-run defeat against India on Wednesday.

But it means that New Zealand go into the last four in good heart, with skipper Kane Williamson beginning to find form after scoring a brisk 42 off 32 balls at the top of the order.

Williamson was the second New Zealand wicket to fall to Rahman, who finished with figures of five for 22.

The opener Henry Nicholls, who was brought in to give Martin Guptill a rest, was the first to go, bowled by Rahman off a slower cutter with the score on 25.

Wiliamson had looked in good nick in an innings that included five boundaries and a six before he was also sent back to the Eden Gardens' dugout at the end of Rahman's first spell.

He was one of a number of the Black Caps' top order who promised to post a big score but were out just as they had finished building their platform.

Colin Munro had been warming up for his first substantial knock of the tournament. But three balls after lofting Al-Amin Hossain into the stands, he had his middle stump removed by the same bowler.  

The veteran Ross Taylor also contributed 28 off 24 balls before being caught by Mohammad Mithun off Hossain.

No other batsman got into double figures and Rahman bowled both Mitchell Santner and McCullum in his final over although his last ball was hammered for six by Mitchell McClenaghan.

The victory ensures New Zealand top their pool and they are now likely to play one of England, Sri Lanka or South Africa in the first semi-final in New Delhi on March 30.

The second semi-final is in Mumbai on March 31 while the final is at Eden Gardens on April 3.