Johannesburg - The Congress of South African Trade Unions (Cosatu) said on Thursday all its affiliated unions had served seven-day notices for a secondary strike, which threatens to bring the country's economy to a halt. Cosatu general secretary Zwelinzima Vavi has warned that the secondary strike will totally shut down the economy. Cosatu said its central executive committee fully supports the public service workers' strike and has agreed to mobilise all Cosatu unions in solidarity action. The union federation said it continued to urge the government to return to the Public Service Coordinating Bargaining Council (PSCBC) with a new offer capable of settling the dispute that has led to the strike. Government is offering a 7% wage increase and a R700 housing allowance, but unions are demanding an 8.6% wage increase and R1 000 housing allowance. Meanwhile, The South African Security Forces Union (Sasfu) said on Thursday that soldiers planned to embark on marches in major cities in an effort to add pressure on the government to improve its wage offer for public servants, but police have lost their bid to partake in mass action. Bhekinkosi Mvovo, Sasfu's president, said the union will decide on Sunday when its 12 000 members will embark on marches in major cities. Mvovo said the union today served municipalities in Durban, Cape Town and Port Elizabeth with notices of marches. Norman Mampane, spokesperson for the Police and Prisons Civil Rights Organisation (Popcru), confirmed that police were not participating in the mass marches throughout the country on Thursday following a court interdict preventing them from doing so.