The meeting between Pakistan's Adviser to the Prime Minister on Foreign Affairs Sartaj Aziz and Afghanistan's National Security Adviser Hanif Atmar was hosted by UK's National Security Adviser Sir Mark Lyall, the Dawn reported.
It is the first high level face-to-face interaction between both countries after Pakistan closed border last month alleging that Afghan-based militants are mounting attacks, the report said.
Pakistan's Foreign Office has said nothing about the meeting so far.
Military sources had said that the militants targeted by them were from Jamaat-ul-Ahrar.
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Complaining about a breach of its sovereignty, the Afghan foreign ministry said Pakistan should stop all cross-border military activity.
The British Foreign Office refused to comment on the meeting in London, but it believed the three men discussed Pakistani complaints that Afghan-based militants had been mounting attacks on Pakistani soil.
Pakistan has blamed the recent Lahore and Sehwan attacks on Afghan-based militants.
The UK is hoping to defuse tensions between the two countries, the report said.
Tighter Pakistan physical and radar-based controls along the 1,100 km border between the Federally Administered Tribal Areas and Afghanistan have made it more difficult for people to cross without going through official crossing points.
The closure of the border has caused heavy financial losses for traders in both countries. Afghanistan depends on Pakistani ports for its imports.
Since the border closure thousands of shipping containers have been stuck in Karachi.