Full-scale 3G services may be delayed in Japan until 2002 or later after the government refused to give NTT DoCoMo permission to launch a full-scale 3G network. The Japanese government took the decision over the weekend. It is concerned that 3G, which will allow users to access high-speed Internet data services from a mobile handset, is too buggy and unstable. The decision is a further blow to the credibility of the third-generation mobile networks, and comes as DoCoMo begins limited 3G trials in Tokyo. DoCoMo is insisting that it will gain government approval in time to launch a full commercial 3G service on 1 October. However, sources suggest that the Japanese Ministry of Posts and Telecommunications could withhold permission until next year, or even later. The ministry is demanding that DoCoMo gives it regular performance updates from its Tokyo 3G tests, and if the company cannot prove that the service works then it will not be granted permission for full-scale rollout. DoCoMo was originally planning to launch its commercial 3G service in on 30 May 2001, but last month it was forced to push the launch date back to 1 October, blaming network instability. Rival BT Wireless has also experienced serious bugs, which have forced it to delay its own 3G launch -- of a trial network on the Isle Of Man -- until October. The most serious problem with the prototype 3G handsets is that they cannot cope with moving between base stations. Users should be able to change location while using the phone, with the network automatically switching the call to another transmitter if required. Because of a software fault, 3G phones are cutting off the call instead. A spokesman from DoCoMo claimed on Tuesday that the company was "convinced we will get the approval" in time for a full launch on 1 October. Official approval isn't required for DoCoMo's 3G trials, which will involve 3,300 users in the Tokyo area. However, the company will not be releasing its much-awaited "Foma" videophones until late June -- and has instead issued testers with modified i-mode phones. There are suggestions from Japan that the trials will be disappointing, because they will not allow the high-speed data transmissions that have been promised. How can you get access to information and entertainment from just about anywhere? Find out the latest in ZDNet UK's Mobile Technology News Section. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the ZDNet News forum. Let the editors know what you think in the Mailroom. And read what others have said.