Sheriff courts will be deluged with cases and suffer delays under plans to overhaul the civil court structure, the body representing lawyers has warned.

Proposals to raise the threshold for cases to be heard by the Court of Session are included in the draft Courts Reform (Scotland) Bill before the Scottish Parliament.

Edinburgh's Court of Session can currently hear civil cases where the sum sued for is £5000 or more, but under the plans only cases valued at more than £150,000 will go to the Court of Session.

The Law Society of Scotland supports an increase in the threshold for Court of Session cases, but says it should be about £50,000.

The Scottish Court Service has already outlined plans to close 10 sheriff courts in a £4 million-a-year cost-cutting programme.

"If the proposals are implemented as currently drafted, a deluge of cases could hit Scotland's sheriff courts," said Kim Leslie, Convener of the Law Society of Scotland's Civil Justice Committee.

"There is a risk sheriff courts will be unable to cope with the volume of new work suddenly arriving at their door. We expect this to be made worse by the recent Scottish Government decision to support the closure of 20% of sheriff courts across Scotland.

"If sheriff courts are unable to cope with the increased workload, there could be significant delays for court users."

Ms Leslie's committee researched the effects of raising the threshold to £150,000. It found only 254 cases settled with a value higher than this figure, representing less than 2% of Court of Session business.

Ms Leslie added: "If the proposals are implemented as currently drafted, we could end up in the paradoxical situation of an almost completely deserted Court of Session, whilst court users in the sheriff courts suffer long delays as the courts struggle to cope with an increased workload. The Scottish Government is right to raise the threshold. However, we would prefer to see the limit set at no more than £50,000."

Sheriff courts in Dornoch, Duns, Kirkcudbright, Peebles, Rothesay, Cupar, Dingwall, Arbroath, Haddington and Stonehaven are earmarked for closure, with their business going to other locations.

Scottish Liberal Democrat justice spokeswoman Alison McInnes MSP said: "On top of the proposals to shut a fifth of our sheriff courts, this reform would strain our sheriff courts to breaking point."

A Scottish Government spokesman said: "The Scottish Government accepted the Scottish Court Service's proposals to change the structure of our courts. Their proposals are now being scrutinised by Parliament.

"The volume of business carried out in the sheriff courts recommended for closure is around 5% of the total business, which [the court service] is confident can be dealt with within a smaller number of better-equipped courts."