BOGOTA (Reuters) - The start of work on Colombian capital Bogota’s first metro line could be delayed by at least six months because companies involved in its construction are affected by quarantine orders to control the spread of the coronavirus, officials said Monday.

Construction will be delayed if an independent controller - who will audit contract awards - is not appointed.

The Bogota Metro Company (EMB) has extended the deadline for six international consortia to submit their bids to be the project’s independent controller to May 27, from April 14 previously.

“The decision (to extend the deadline) was taken due to operating and travel restrictions in the face of the COVID-19 pandemic,” the EMB said in a statement.

The different consortia include companies from Spain, Germany, the United States, Mexico and Brazil.

The contract for building the first metro line in Bogota, which will cost some 13.8 trillion pesos ($3.55 billion) was awarded last October to the Apca Transmimetro consortium, which is led by Chinese companies Harbour Engineering Company Ltd.(CHEC) and Xi’an Metro Co. Ltd.

EMB manager Andrés Escobar explained that work to build the metro cannot begin without an auditor.

“If the tender to select the independent controller is unsuccessful, another tender would have to be held and the start of works would be delayed for at least six months,” Escobar said in a statement.

The metro, which has been fought over by politicians for years, is considered a crucial project in reduce Bogota’s chaotic traffic. The city has more than 7 million inhabitants and the metro will complement the TransMilenio bus system.

Bogota Mayor Claudia Lopez previously estimated that the first metro line will be ready in 2028.

(This story refiles to correct mayor’s name to Claudia Lopez from Claudio Lopez)