At least 12 more men have died after drinking adulterated cough syrup in Pakistan's Punjab province, taking the death toll since last month to 40, officials said today.

The total number of deaths this week has risen to 20, health officials said.

Eighteen deaths occurred in Gujranwala and Toba Tek Singh districts and the remaining in the provincial capital of Lahore.

Another 40 men are being treated in several hospitals.

Twenty men, a majority of them drug addicts, died in Lahore last month after drinking the Tyno cough syrup.

The latest deaths involved a cough syrup named Dextromethorphan, Punjab Health Secretary Arif Nadeem said.

The deaths in Gujranwala and Toba Tek Singh were very similar to those in Lahore, he said.

Nadeem said an excessive dose of the active ingredient in cough syrups had resulted in the deaths.

He claimed that this ingredient was imported from two countries – China and India – to manufacture cough syrups in Punjab and other parts of Pakistan.

Muhammad Ashraf, the Executive Health Officer of Gujranwala district, said: "We have confiscated stocks of the killer syrup after raiding most pharmacies in the district."

This was the third instance of deaths caused by drugs in Punjab this year.

Several months ago, over 150 cardiac patients died after taking bad drugs provided by the Punjab Institute of Cardiology.

Chief Minister Shahbaz Sharif's government ordered an inquiry into the incident, but it neither made its report public nor took action against anyone.