UPDATE 7-Smoke pours from Kenya mall as forces "close in"
* Loud blasts, then thick smoke billows from mall
* Interior minister says militants started fire, siege nears end
* Some gunmen dressed as women, no women among attackers
* Unclear how many hostages being 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 James Macharia
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, three days after a raid by Somalia's al Shabaab killed at least 62 people.
It remained unclear how many gunmen and hostages were still cornered in the Westgate shopping centre, two hours after a series of loud explosions and gunfire were followed by a plume of black smoke, that grew in volume from one part of the complex. Continued...