LU said up to 100 trains out of the normal 500 ran in the morning peak, while long queues built up at bus stops across the capital and traffic was heavier than usual on roads into central London.
Tim O'Toole, managing director of LU, said: "I am sorry for the difficult journey many passengers are having to face today. We are encouraged by the number of train drivers at work, which is allowing us to run more services than we expected and I would like to thank those staff who are keeping London moving."
Dozens of extra buses were laid on and the entire fleet of 8,000 buses was out on the roads this morning, carrying what is expected to be a record number of passengers. Tube services began running down shortly after the strike started at 6.30pm last night and are expected to be affected into this evening, well after the strike ends.
The general secretary of the Rail, Maritime and Transport union, Bob Crow, again called on London mayor Ken Livingstone to become personally involved in the dispute over pay and conditions.
"We need someone with the authority and the inclination to hammer out a deal. Instead, we continue to bang our heads against a brick wall with a management that Mr Livingstone wants dismissed as dullards and knuckleheads," Mr Crow said.
Mr Crow, who was attending his union's annual conference in Portsmouth today, said the solution to the dispute was "not very difficult". The union wanted a 35-hour week for all its members and "unacceptable" strings removed from the deal.
The union maintained that 800 jobs would be lost under the proposed agreement as well as the "wholesale slaughter" of working conditions.
Mr Livingstone, who walked to his office near Tower Bridge because of the strike, described the offer of a 6.75% pay increase over two years and a reduction in hours to 35 a week by 2006 as "incredibly generous".
Workers across the country would be happy to accept such a deal, which also guaranteed the company's final salary pension scheme, he said. "If the answer to this question is a strike, I think perhaps the union is asking the wrong question," he added.
Mr Livingstone said 200 jobs would be lost under the deal and he turned down union demands for a four-day week, claiming it would lead to higher tube fares.
As strikers gathered at picket lines across the capital, business leaders criticised the strike for its effect on London's economy.
Maurice Fitzpatrick, head of economics at accountancy firm Numerica, estimated that the cost of the strike to the capital would be £100m.
