BMA leaders said the offer released by the government and NHS Employers had not been discussed with them, and called on ministers to drop the threat of an imposed contract.
The offer comes as the BMA prepares to ballot junior doctors on Thursday over potential industrial action in protest over pay reforms.
Mr Hunt has pledged that GP trainees will not lose out under the reforms, despite plans to scrap the existing GP training supplement.
Junior doctor contract
A document setting out the government's proposed pay deal says: 'A flexible pay premium for general practice will replace the current GP training supplement, operating in much the same way and set at a value which preserves the parity in pay that GP trainees enjoy at present.'
It adds: 'The application of the flexible pay premium as described above, coupled with an offer of pay protection on transition, will maintain current earnings for existing GP trainees.'
Junior doctors' basic pay would increase from £22,636 to £25,500 under the offer released by the government and NHS Employers last night.
The current pay banding scheme would be scrapped and doctors would progress through five pay progression points to a salary of £55,000 in the final stage of training compared with £47,175 now.
GP trainee guarantee
The changes would mean that 'successful progress through training and taking up a post at the next level of responsibility will replace automatic annual increments', according to a DH statement, meaning that junior doctors would 'no longer get an automatic pay increase every year regardless of acheivement and performance'.
The offer makes a concession on working hours, too. A government statement says: 'The government has decided that plain time will be extended until 7pm Saturday instead of 10pm Saturday. Doctors will receive time and a half for any hours worked Monday to Sunday between 10pm – 7am, and time and a third for any hours worked between 7pm-10pm on Saturday and 7am-10pm on Sunday.'
Pay will be topped up further by 'on call availability allowances' worth between 2% and 6% of basic pay.
BMA junior doctors committee chairman Dr Johann Malawana hit out at the government's decision to release the first details of the deal via the media at the 'eleventh hour' before the strike ballot.
Junior doctor industrial action
'We have repeatedly asked for such detail in writing from the health secretary, but find instead that this has been released to media without sharing it with junior doctors’ representatives. Jeremy Hunt has repeatedly changed his position on pay and just last week was caught out trying to gloss over the truth when he said that no doctor would have their pay cut, only hours later to admit that those working the longest hours would in fact see a reduction in pay.
'The BMA and junior doctors have been clear that we want to reach a negotiated agreement with the government on a contract that is good for patients, junior doctors and the NHS. In order to do this we have said, repeatedly, that the government must remove the threat of imposition and provide the concrete assurances junior doctors have asked for on a contract that is safe and fair.
'We are clear that without the assurances we require, the BMA will be left with little option but to continue with our plans to ballot members. The government have so far failed to provide these reasonable assurances, preferring instead to engage in megaphone diplomacy and plough ahead with plans to impose a contract that would be bad for patients as well as junior doctors.'
NHS Employers chief executive Danny Mortimer said: 'We have written to Dr Johann Malawana setting out a firm offer for a new junior doctors contract in England. We have worked with the DH to develop an offer that is fair and safe for patients and doctors. We want to work with the BMA now to agree the final details of the contract by the new year.'
NHS Employers has released a video explaining the junior doctors contract deal, and set up a Facebook page.