The death toll in a Mexican pipeline fire has risen to 29, Mexico's state-owned oil company said on Wednesday.
At least 46 others were injured at a distribution plant near the US border, and more might still be missing.
Two of the injured were reported in serious condition.
Petroleos Mexicanos director Juan Jose Suarez said that at least five workers had not been seen since the blast.
Mexican President Felipe Calderon said the quick reaction of emergency teams prevented a "real catastrophe" by controlling the fire before it reached the huge tanks of a neighbouring gas processing plant.
Pemex officials said the blast appeared to have been caused by an accidental leak, and there was no sign so far of sabotage.
The Mexican Attorney General's Office has opened an investigation into the explosion, sending more than 20 investigators to the site.
Foreign Minister Alistair Burt's admission that the Cameron government has "supported" a survey of attitudes to US drone strikes in Pakistan's tribal areas amounts to a tacit admission of British involvement.