City law firms are warning of delays in completing deals following the closure of records office Companies House in London.
The shutdown, say firms, is bound to hold up transactions. Hard copies of documents will be available from Companies House in Cardiff.
But lawyers say delays getting details to London will affect mergers and acquisitions. Those advising US-based clients are expected to be particularly hard hit because of the time difference.
Searches can be performed on the internet, but lawyers say only microfiche hard copies are legally binding.
A Dibb Lupton Alsop spokeswoman says the closure will cause delay and expense to law firms because "fee earners need to see the most recent version of the microfiche".
A Slaughter and May spokeswoman says: "We take the view that it is better to rely on fiches as the online version is not going to be complete."
Malcolm Godwin, senior partner at Cardiff company law agency Severnside, which arranges for information in Cardiff to reach firms, says: "Online information has its uses but only gives part of the picture. Worse than that it can give a misleading impression, which can be dangerous."
ICC Information, which has bought the Companies House London stock of microfiches, denies there will be delays.
ICC promises instant copies of microfiches on demand and 11 of the top 20 law firms have signed up to its service, including Freshfields and Simmons & Simmons.
Companies House is providing more deliveries to reduce the impact of the move. Chief executive John Holden says: "This new microfiche service will complement and reinforce the online service. Together, they should ensure that our London customers continue to receive a comprehensive and efficient service."