Islamabad, Sep 18 - Pakistan has lodged a strong protest with India over an 'unprovoked' firing by the Indian Border Security Forces (BSF) at a Pakistani checkpost near the Sialkot international boundary, a media report said Friday.

Pakistan has also demanded a flag meeting between the two sides to investigate the matter.

The Online news agency, citing Pakistani interior ministry, said that the Indian security forces have violated a ceasefire agreement by firing at the Pakistani Rangers Thursday night in the Pokhlian sector near Sialkot.

The Pakistani Rangers retaliated and the exchange of fire lasted for about four hours. No loss of life was reported, it said.

The BSF again started firing at the checkpost Friday morning, the report said citing sources.

Meanwhile, senior Pakistani security officials have rejected the Indian media reports that it was the Pakistani side that started the firing first. They said no BSF soldier was injured in the incident.

IANS had earlier reported quoting a senior BSF official that firing continued Friday from the Pakistani side on the Nikowal border post, about 30 km west of Jammu city.