In a breakthrough in the tunnel collapse rescue operation in Telangana that has been going on for a week, the whereabouts of four of the total eight persons trapped has been located, state Excise Minister Jupally Krishna Rao said on Saturday.

Krishna Rao, who attended a meeting with officials involved in the rescue operation along with Irrigation Minister N Uttam Kumar Reddy, said there was lot of progress during the last couple of days.

"In my view, the whereabouts of four persons have been located through radar," he told reporters at the tunnel. He expressed hope they would be extricated by Sunday evening.

The other four appear to have been stuck beneath the Tunnel Boring Machine (TBM), he said.

Asked about the condition of the four whose whereabouts have been found, the minister recalled he had said on the first day itself that the chances of survival are remote.

The 450 ft tall TBM was being cut, he said.

The personnel of about 11 agencies are involved in the operation.

Referring to the criticism of opposition parties that the operation is getting delayed, Krishna Rao said those involved in the endeavour are experts but the rescue work is complex in view of the conditions, including slush, inside the tunnel.

Eight persons--engineers and labourers have been trapped under the collapsed roof of the Srisailam Left Bank Canal (SLBC) tunnel since February 22 and the rescue operations are on in full swing to pull them out to safety.

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