Police on Thursday arrested on murder charges the mother of the two siblings who died after consuming Napa syrup in Brahmanbaria.

The deaths of the two children shook the entire country and raised a question over the quality of Napa syrup.

Read:Napa deaths: DGDA claims syrup was safe

Police claimed that Lima Begum had killed her two children over an extra-marital affair. 

"Our team nabbed Lima, the mother of the two children, from her house in Ashuganj upazila of the district this morning," said additional superintendent of Brahmanbaria Police, Molla Mohammad Shaheen.

The arrest came following an investigation which revealed that Lima had developed an illicit affair with a man, named Shafiullah, while working at a local rice mill, the police officer told the media.

"Lima and the man wanted to get married. And to make their plan successful, Lima offered sweetmeat laced with poison to her two children, which caused their deaths,"  Shaheen said.

While Lima has admitted her guilt during questioning, efforts are on to arrest Shafiul, said Shaheen.

Ismail Khan, the father of the two children, had lodged a complaint at the Ashuganj police station, following the deaths of their two children. Based on the complaint, an FIR was registered by police.

On March 10, the two siblings -- Yasin Khan, 7, and Morsalin Khan, 5 -- allegedly died after consuming Napa syrup at their home as they were down with high fever.

It was bought from the local ‘Ma Pharmacy’ owned by Main Uddin.

The children were discharged after being given primary medications at District Sadar Hospital. Yasin died on the way home, and Morsalin after reaching home, the family said.

Read: Health Minister vows legal action in Napa deaths of two siblings

Two probe bodies have been formed in this connection, while samples of the syrups of the same batch were collected for testing.

After testing, officials of the Directorate General of Drug Administration (DGDA) on Monday said the batch of the Napa syrup was found to be "safe".