British troops are expected to be part of a multi-national task force responsible for verifying Hezbollah has disarmed, paving the way for Israel to withdraw from the region.
Israel and Lebanon are reported to have agreed that the UK will join the team which will also include representatives from Italy, Switzerland and Indonesia.
Hezbollah’s disarmament is a crucial part of a deal drawn up in June which would enable Israel’s phased withdrawal from Lebanon.
The shortlist of countries was put together at talks in Rome mediated by the US last week.
The countries selected could help define the scope of the verification process, provide personnel to oversee it or contribute troops to observe or take part in inspections.
A Lebanese official told Reuters Israel and Lebanon had agreed on a list of potential countries that could send troops and said the US would ultimately decide which of them would take part.
The deal drawn up in June between Israel and Lebanon is part of Washington's efforts to end the conflict between Israel and Hezbollah, triggered in March when the Iran-backed Lebanese armed group attacked Israel following the start of the US and Israeli war with Iran.
A source said discussions surrounding the shortlisted countries were in the early stages but said that they were "cautiously optimistic".
A spokesperson for Israel's Embassy to the United States said in a statement that negotiations over the composition of the body that would oversee and verify Hezbollah's disarmament were ongoing and that no agreement had yet been reached.
Switzerland's foreign ministry told Reuters it was exploring ways to support "various stabilisation processes", but declined to provide details.
A British foreign ministry spokesperson said Britain was ready to support efforts to de-escalate tensions and long-term security, particularly in southern Lebanon.
The Lebanese presidency and the Indonesian foreign ministry did not immediately respond to requests for comment.
Israel's military occupies what it describes as a security zone extending six miles into southern Lebanon and has said it will not withdraw unilaterally until Hezbollah is disarmed.
Sources said that under the proposed mechanism, villages in southern Lebanon would be inspected and verified as being free of weapons.
Israel wants those inspections to include private homes, which the Lebanese army has previously resisted.
A foreign security official said the question of private properties would need addressing, including how and by whom they would be searched.
The official said the extent of foreign troops' freedom of movement would also need to be clearly established.
To get more news, click here to sign up for our free daily newsletter.