WEST, the United States - Sixty people remained unaccounted for after Wednesday's explosion at a fertilizer plant in the US state of Texas, a US senator said on Friday.

At a midday news briefing, local officials declined to provide an accurate figure of deaths from the deadly blast in the city of West, but Senator John Cornyn confirmed that 60 people "remained unaccounted for."

Cornyn said that authorities are still checking hospitals and " making sure they know where people are."

Authorities expect the number of people unaccounted for to come down, he added.

Twelve people have been confirmed dead in the explosion, and 25 houses in the blast area remain to be searched, officials said here earlier on Friday.

The powerful blast occurred around 7:50 pm local time Wednesday at a fertilizer plant in West, a small town some 320 km north of Houston. It also left about 200 people injured.