The Indian government is due to honour a seven-year-old police dog who has impressed security officials with his ability to sniff out explosives.

Rex, a black Labrador, is the "top dog" in the K9 (canine) unit of Indo-Tibetan Border Police (ITBP), security officials told the BBC.

Rex was a part of the team of 20 dogs which was used to secure the venue of the recent India-Africa summit.

The K9 unit is regularly used for anti-sabotage work at big-ticket events.

"At the venue of the India-Africa summit, Prime Minister Narendra Modi's security officials planted five grams (1/10th of an ounce) of RDX explosives under his chair as part of the security drill," a senior police official told the BBC.

"Rex found it in two minutes. The PM's security was overjoyed," he said.

Officials say the K9 unit is routinely deployed to sniff out explosives and secure venues during high-profile events and visits by foreign leaders.

The dogs were used during "Operation ObMo" (when US President Barack Obama visited Delhi and met PM Modi), "Operation Doga" (International Yoga Day), and during the Independence Day and Republic Day celebrations, they said.