UPDATE 9-Smoke pours from Kenya mall as forces "close in"
* Loud blasts, then thick smoke billows from mall
* Minister says militants started fire, siege nears end
* Unclear how many hostages held, death toll at least 62
* Somali Islamists linked to al Qaeda claim responsibility
* Group wants withdrawal of Kenyan troops from Somalia
By Matthew Mpoke Bigg and Richard Lough
NAIROBI, Sept 23 (Reuters) - Thick smoke poured from the besieged Nairobi mall where Kenyan officials said their forces were closing in on Islamists holding hostages on Monday, the third day since Somalia's al Shabaab launched a raid that has killed at least 62 people.
It remained unclear how many gunmen and hostages were still cornered in the Westgate shopping centre, after a series of loud explosions and gunfire were followed by black smoke billowing from one part of the complex.
Following a pattern of the past three days, bursts of gunfire and activity have been followed by long lulls. Continued...