By Shahid Malik in Lahore

The trial of Pakistan's alleged serial killer, Javed Iqbal, heard evidence on Monday from a shopworker who said he sold acid to one of Mr Iqbal's co-accused.

Mirza Nazir Beg, an employee of a shop selling chemicals in Lahore, appeared as a prosecution witness.

He testified that one of Mr Iqbal's alleged accomplices, 16-year-old Shahzad Sajid, had visited the shop to buy sulphuric and hydrochloric acid.

He said Mr Sajid paid cash for the acid and was given a receipt for every purchase.

Mirza Nazir Beg said the shop did not keep copies of cash receipts, though they did maintain records of the daily turnover and an inventory of the goods sold.

The prosecution says that Javed killed 100 teenagers and destroyed their bodies by throwing them into drums containing acidic liquid.

Police recovered the mutilated remains of human bodies from two plastic drums in Mr Iqbal's house after he confessed to the killings in a letter to a newspaper nearly three months ago.

Traumatic testimonies

Ten days into the trial, the prosecution has produced more than 80 witnesses, as many as 55 of them parents or family members of the children missing, presumed killed.

Most of the evidence, however, has been of a circumstantial nature.

Another two relatives of missing boys gave evidence on Monday, along with the person who developed and printed some films recovered from Mr Iqbal's house.

Mr Iqbal has now recanted his earlier confession and pleaded innocent.

Three alleged accomplices - all in their teens - have denied charges of murder, abduction and sodomy.

Earlier in the day, four prosecution witnesses were examined in another case, in which Mr Iqbal has been charged with abduction and sodomy.

These charges were brought against him in connection with a separate case involving two brothers, who are still alive and are not included in the case of 100 alleged victims.