(reuters) -- Banking sources said some banks from Saudi Arabia, the United Arab Emirates and Bahrain delayed letters of credit and other deals with Qatari banks after their governments cut diplomatic ties and transport links with Doha on Monday, accusing Qatar of backing terrorism.

Saudi Arabia's central bank advised banks in the kingdom not to trade with Qatari banks in Qatari riyals, the sources told Reuters. The central bank did not respond to a request for comment.

Qatar has dismissed the terrorism charge and welcomed a Kuwaiti mediation effort. Doha, the world's biggest liquefied natural gas exporter, says it has enough reserves to support its banks and its riyal currency, which is pegged to the dollar.

Qatari banks have been borrowing abroad to fund their activities. Their foreign liabilities ballooned to 451 billion riyals ($124 billion) in March from 310 billion riyals at the end of 2015, central bank data shows.

So any extended disruption to their ties with foreign banks could potentially threaten a funding crunch for some Qatari banks. Banks from the UAE, Europe and elsewhere have been lending to Qatari institutions.

[persian] Gulf banking sources, who declined to be named because of political sensitivities, said Saudi Arabian, UAE and Bahraini banks were postponing deals until they received guidance from their central banks on how to handle Qatar.